Math & Engineering Calculators

Use these calculators for math, health, and everyday life. Math covers basic and scientific calculator, percentage, average, fraction, statistics, probability, number calculators, geometry, and algebra. Architecture, Construction, HVAC, and Plumbing offer trade and building calculators. Health covers BMI, BMR, calorie, fitness, pregnancy, and lifestyle. Calculators & Daily includes date & time, travel, outdoors, kitchen, school, size converters, and random generators. Energy, Solar, Electrical, Mechanical, and Science & Engineering cover power, solar, and technical calculations. Search or pick a category below to start.

Tools by category

Basic Calculator

Basic arithmetic • send result to unit converter

Basic Scientific

0

History

No calculations yet

Scientific Calculator

Trig, logarithms, powers, constants

Scientific mode is available inside the Calculator. Toggle it with the Scientific button above the keypad.

Programmer Calculator

Hex, binary, octal, decimal • bitwise • shifts • word size

0

HEX: 0000 0000

DEC: 0

OCT: 000 000 000 00

BIN: 0000 0000 0000 0000 0000 0000 0000 0000

Signed: 0

Bit view · click to toggle

What it does

Work with numbers in hex, decimal, octal, and binary and perform bitwise and arithmetic operations for programming and low-level work.
Choose an input base (Dec, Hex, Bin, Oct) and word size (8/16/32/64-bit); the value updates in all bases. Use the bit grid to toggle bits or the keypad for digits and operators.
Supports arithmetic (+, −, ×, ÷, mod), bitwise (AND, OR, XOR, NOT), shifts, rotations, and unary ops so you can match common integer types and workflows.

FAQ

What is a programmer calculator?

A calculator that works in hex, binary, and octal as well as decimal, and supports bitwise and shift operations used in programming.

What are the number bases used for?

Decimal is everyday numbers; hex and binary are common in code (addresses, masks, flags); octal appears in some file permissions and legacy systems.

What does word size do?

Word size (8, 16, 32, 64 bits) limits the value range and how results are displayed, matching common integer types (e.g. uint32_t, int64_t).

Related tools

The tools and simulations on Calciverse are provided for informational and educational purposes only and should not be considered financial, investment, tax, or legal advice. Results are estimates based on user inputs and assumptions and may not reflect real-world outcomes. Users should consult qualified financial, tax, or legal professionals before making any financial decisions. Use of Calciverse is at your own risk.

GRAPH SYSTEMS OF EQUATIONS (CALCULATOR + INTERACTIVE GRAPH)

Graph two equations to find intersections: solutions to systems. Plot two lines with paired curves on an interactive graphing calculator.

f(x) =

Use * for multiplication (e.g. 2*x). Powers use ^ (e.g. x^2). Functions include sin, cos, tan, sqrt, abs, log, exp.

Examples:

Systems combine multiple equations. Plotting two curves makes candidate solutions visible before algebra confirms them.

This page demonstrates two lines with a preset pair. Editing the main function may hide the second line unless you reset to defaults.

Move to inequalities when you need regions instead of intersection points.

Quick answer

Real solutions to a system appear where graphs intersect. Two lines typically meet at a single point unless parallel or coincident.

What it does

Plot the default pair and read the crossing approximately.
Zoom near the intersection for better accuracy.
Substitute into both equations to verify.
Try nonlinear systems by plotting other families on separate visits.

Examples

y = 2*x + 1 with y = -x + 3
Try y = x
Try y = x^2
Reset for the line demo

FAQ

Can I plot three or more curves?

v1 supports up to two curves with the companion line. Plot additional equations sequentially for sketches.

What if lines are parallel?

There is no intersection (unless coincident with infinitely many solutions).

Related tools

The tools and simulations on Calciverse are provided for informational and educational purposes only and should not be considered financial, investment, tax, or legal advice. Results are estimates based on user inputs and assumptions and may not reflect real-world outcomes. Users should consult qualified financial, tax, or legal professionals before making any financial decisions. Use of Calciverse is at your own risk.

Percentage Calculator

Common phrases, percentage difference, and increase/decrease by percent.

What is X% of Y?

X (%)

Y (value)

Result

—

Formula: Result = (X/100) × Y

X is what % of Y?

X

Y

Percentage

—

Formula: Result = (X / Y) × 100

Percentage Change (X → Y)

From (X)

To (Y)

Change

—

Type

—

Formula: Change % = ((Y − X) / X) × 100

X is Y% of what?

X (value)

X (%)

Whole

—

Formula: Whole = X / (Y/100)

Percentage Difference

Value 1

Value 2

Difference

—

Increase or Decrease by Percent

Value

Percent (%)

Type

Increase Decrease

Result

—

Percent Error

Accepted (actual) value

Measured (observed) value

Percent Error

—

Formula: Percent Error = |measured − accepted| / |accepted| × 100

Fraction Calculator

Add, subtract, multiply, divide fractions; simplify; convert between decimal and fraction.

Numerator 1

Denominator 1

Operation

Numerator 2

Denominator 2

Fraction

—

Decimal

—

Mixed number

—

Statistics Calculator

Mean, median, mode, standard deviation & more

Numbers (comma or space separated)

Area & Volume

Geometric area and volume by shape. Select a shape, enter values, then click Calculate.

Area Volume

Geometric shape

Result

—

Surface Area

Surface area of sphere, cone, cube, cylinder, prism, capsule, cap, frustum, ellipsoid, pyramid. Same unit for all dimensions.

Shape

Formula

Surface Area

—

Average Calculator

Mean, weighted average, and rolling totals

Numbers (comma separated)

Lorem Ipsum Generator

Generate placeholder text — words, sentences, or paragraphs

Type

Count

Home & Rent Affordability

Big financial decisions — how much house or rent you can afford: income and debt → max home price or max monthly rent. Combines house affordability, rent affordability, and DTI.

Affordability type

I want to see

How much house I can afford (buy) How much rent I can afford (rent)

Income & debt

Annual household income ($)

Monthly debt payments ($)

Loan & costs

Loan term (years)

Interest rate (APR %)

Down payment (%)

Property tax (% of price/yr)

Home insurance ($/yr)

HOA ($/yr)

DTI rule

Qualification rule

Reverse: target home price

Target home price ($, optional)

Comparison

What if income were ($/yr)

Price tiers

Monthly payment at max price

Required income (target price)

Financial health

Approval strength

Lifestyle impact

Down payment

Income comparison

Budget breakdown

Loan & Mortgage

Big financial decisions — conventional, FHA & VA loans with taxes, insurance, PMI/MIP, payoff, refinance and APR views.

Tip Calculator

Split bills and calculate tips

Bill Amount ($)

Tip (%)

Number of People

Bill vs Tip

Discount Calculator

Find sale price, savings, and effective discount for single or stacked discounts.

Original Price ($)

Discounts (%)

Tip: Enter one discount for a single sale, or multiple comma-separated discounts for stacked discounting.

Find Discount % from Prices

Original Price ($)

Sale Price ($)

Home Equity & HELOC

Big financial decisions — available equity, Home Equity Loan vs HELOC comparison, costs over time, stress tests, and a clear recommendation.

Your home

Current home value ($)

Mortgage balance ($)

LTV lenders will use (%)

Borrow amount ($)

Use max available equity

Home Equity Loan

Interest rate (%)

Term (years)

Closing costs ($)

HELOC

Interest rate (%)

Draw period (years)

Repayment period (years)

Closing costs ($)

Annual fee ($)

Best loan payment plan

HELOC draw & repayment

Total cost over time

Net cash & equity

Payment stress test

HELOC sensitivity

Equity vs loan balance

Payment timeline

Recommendation

Rent vs Buy

Big financial decisions — compare average monthly cost of buying vs renting over 1–30 years; break-even and chart

Home purchase

Home Price ($)

Down Payment (%)

Interest Rate (%)

Loan Term (years)

Buying Closing Costs (%)

Selling Closing Costs (%)

Property Tax (%/yr)

Property Tax Increase (%/yr)

Home Insurance ($/yr)

HOA ($/yr)

Maintenance (%/yr)

Home Appreciation (%/yr)

Cost/Insurance Increase (%/yr)

Home rent

Monthly Rent ($)

Rent Increase (%/yr)

Renter Insurance ($/mo)

Security Deposit ($)

Upfront Cost ($)

Your info

Investment Return (%/yr)

Federal Tax Rate (%)

State Tax Rate (%)

Filing Status

Average cost Net worth impact

Include tax effects Include investment returnHorizon

Chart

Average cost by stay length

Staying Length	Average Buying Cost		Average Renting Cost
Staying Length	Monthly	Annual	Monthly	Annual

Assumptions: fixed-rate fully amortizing mortgage with level payments; investment return is applied to upfront cash as annual compound growth; property tax and insurance grow using the inputs above; tax savings are approximated as (mortgage interest + property tax) × (federal + state marginal rate).

Unit Price

Compare price per unit (e.g. $/oz, $/kg)

Price ($)

Quantity

Unit

Trip Cost Calculator

Trip cost, fuel needed, or MPG from distance and fuel used. Use for drive planning and travel budgets.

Distance

Unit

Fuel used (optional)

Fuel used unit

Fuel efficiency (if no fuel used)

Efficiency unit

Fuel price ($/gal or $/L)

Meeting Cost Calculator

Estimate the cost of a meeting from attendees, average hourly rate, and duration.

Number of attendees

Average hourly rate ($)

Duration (minutes)

Speed Calculator

Distance and time → speed; or speed and time → distance

Mode

Distance + Time → Speed Speed + Time → Distance

Distance

Dist unit

Time (hours)

Time (minutes)

Engine Horsepower Calculator

Estimate vehicle HP from weight and 1/4‑mile trap speed (elapsed time optional)

MetricImperial

Vehicle weight (lb)

Trap speed (mph, 1/4 mi)

Elapsed time (sec, optional)

Rounding

Round to N decimal places or significant figures

Number

Mode

Decimal places Significant figures

N

Scientific Notation Calculator

Convert between decimal and scientific notation

Decimal number

Scientific notation

Big Number Calculator

Add, subtract, multiply, divide large integers (beyond normal precision)

Number A

Operation

Number B

Result

—

Half-Life Calculator

Decay: N = N₀ × 0.5^(t / t½). Enter any three to find the fourth.

Initial amount (N₀)

Remaining amount (N)

Half-life (t½)

Time elapsed (t)

Formula: N = N₀ × 0.5^(t / t½)

Slope Calculator

Slope and line equation from two points

x₁

y₁

x₂

y₂

Formula: m = (y₂ − y₁) / (x₂ − x₁); line: y = mx + b

Distance Calculator

Distance between two points (2D, 3D, or latitude/longitude on Earth)

Mode

2D 3D Lat/Long

Point 1:

x₁

y₁

Point 2:

x₂

y₂

Distance

—

Formula: d = √((x₂−x₁)² + (y₂−y₁)²) [add +(z₂−z₁)² for 3D]

Matrix Calculator (2×2)

Determinant, inverse, multiply two 2×2 matrices

Mode

a₁₁

a₁₂

a₂₁

a₂₂

Formula: det = a₁₁a₂₂ − a₁₂a₂₁; A⁻¹ = (1/det)×adj(A); C = A×B

Number Sequence Calculator

Analyze a list, or compute Arithmetic / Geometric / Fibonacci

Mode

Sequence

Next N terms

Sample Size Calculator

Find sample size n or margin of error E for proportion

Find

Proportion (p), 0–1

Margin of error (E), 0–1

Confidence

Population (N), optional

Formula: n = z²×p(1−p)/E²; with finite population N: n = n∞/(1+(n∞−1)/N); E = z×√(p(1−p)/n) or with FPC: ×√((N−n)/(N−1))

Probability Calculator

Two events (P(A), P(B)) or normal distribution (area between bounds)

Mode

P(A)

P(B)

P(A and B)

Formulas: Two events: P(A∪B)=P(A)+P(B)−P(A∩B); P(AΔB)=P(A)+P(B)−2P(A∩B); Series: P(all)=p^n, P(at least one)=1−(1−p)^n; Normal: P = Φ((Rb−μ)/σ) − Φ((Lb−μ)/σ)

Z-Score Calculator

z = (x − μ) / σ

Value (x)

Mean (μ)

Std dev (σ)

Formula: z = (x − μ) / σ

Confidence Interval Calculator

Mean ± Z × (s / √n). For population mean from sample.

Sample mean (x̄)

Sample std dev (s)

Sample size (n)

Confidence

Formula: CI = x̄ ± z × (s/√n); margin = z × (s/√n)

Ratio

Simplify ratio, solve proportion, or ratio to percentage

Mode

Ratio (e.g. 12 : 18)

Linear & Quadratic Equation

One linear (ax + b = c), quadratic ax² + bx + c = 0, or linear systems 2×2 / 3×3

Mode

a

b

c

Solves ax + b = c → x = (c − b) / a

a

b

c

Eq1: x

y

=

Eq2: x

y

=

Eq1

=

Eq2

Eq3

Permutation & Combination

nPr and nCr

n

r

Prime & Factors

Check prime, list factors, LCM, GCD

Number

Second (for LCM/GCD)

Ohm's Law

V = I × R. Enter any two to find the third and power

Voltage (V)

Current (A)

Resistance (Ω)

Formula: V = I × R; P = V × I

Decibel (dB)

dB to power/voltage ratio and back

dB

Type

Formula: Power ratio = 10^(dB/10); Voltage ratio = 10^(dB/20)

Density

Mass, volume, density. Enter two to find the third

Mass (kg)

Volume (m³)

Density (kg/m³)

Formula: ρ = m / V (density = mass / volume)

Molarity Calculator

Molarity (M), moles, volume. Enter two to find the third

Molarity (mol/L)

Moles (mol)

Volume (L)

Formula: M = n / V (molarity = moles / volume in L)

Molecular Weight Calculator

Sum atomic masses from chemical formula (e.g. H2O, CaCO3)

Formula

Dilution (C₁V₁ = C₂V₂)

Enter three of concentration/volume to find the fourth

C₁ (mol/L)

V₁ (L)

C₂ (mol/L)

V₂ (L)

Formula: C₁V₁ = C₂V₂

Solution Mixing

Mix two solutions to get final concentration

C₁ (mol/L)

V₁ (L)

C₂ (mol/L)

V₂ (L)

Mass Percent

Mass of solute / total mass × 100

Mass solute (g)

Mass solution (g)

ppm / ppb

Parts per million or billion from mass or concentration

Mass solute (g)

Mass solution (g)

Unit

Moles (mass ↔ moles)

n = m / M (moles = mass / molar mass)

Mass (g)

Molar mass (g/mol)

Moles (mol)

Formula: n = m / M

Limiting Reactant

Compare moles / stoichiometric coefficient to find limiting reactant and theoretical yield

Moles A

Coeff. A

Moles B

Coeff. B

Ideal Gas Law (PV = nRT)

Enter three of P, V, n, T to find the fourth. R = 0.08206 L·atm/(mol·K)

P (atm)

V (L)

n (mol)

T (K)

Formula: PV = nRT

Gas Density

ρ = PM / (RT): density from pressure, molar mass, temperature

P (atm)

M (g/mol)

T (K)

Gas Cylinder Duration

Estimate time until cylinder empty at given flow rate (simplified: ideal gas)

Cylinder volume (L)

Pressure (atm)

Flow rate (L/min)

pH from [H⁺]

pH = −log₁₀[H⁺]; enter [H⁺] in mol/L

[H⁺] (mol/L)

Formula: pH = −log₁₀[H⁺]

pH Adjustment

Amount of strong acid/base to add to reach target pH (simplified: pure water or buffer)

Volume (L)

Current [H⁺] (mol/L)

Target [H⁺] (mol/L)

Add

Buffer (Henderson–Hasselbalch)

pH = pKa + log₁₀([A⁻]/[HA])

pKa

[HA] (mol/L)

[A⁻] (mol/L)

Specific Gravity

SG = ρ / ρ_ref (default ρ_ref = 1000 kg/m³ for water)

Density ρ (kg/m³)

Reference ρ (kg/m³)

Molar Mass to Density

Density from molar mass and molarity (ρ ≈ M × C for dilute aqueous; or enter mass/volume)

Molar mass (g/mol)

Molarity (mol/L)

Solvent density (g/mL)

Batch / Scale Recipe

Scale recipe by factor: new amount = base amount × scale

Base amount

Scale factor

Yield

Percent yield = (actual / theoretical) × 100

Actual amount

Theoretical amount

Purity

Purity % = (pure mass / total mass) × 100

Pure mass (g)

Total mass (g)

Faraday's Law

Q = n_e × F; charge from moles of electrons (F ≈ 96485 C/mol)

Moles of electrons

Charge Q (C)

Electroplating

Mass deposited: m = (I × t × M) / (n × F); I=current (A), t=time (s), M=molar mass, n=electrons per ion

Current I (A)

Time (s)

Molar mass (g/mol)

n (electrons)

Chlorine Dosing

Mass or volume of chlorine needed for target ppm (e.g. pool)

Volume water (L)

Target ppm

Cl concentration (%)

Water Hardness

Convert Ca²⁺ and Mg²⁺ to mg/L as CaCO₃ equivalent

Ca²⁺ (mg/L)

Mg²⁺ (mg/L)

Alkalinity

Alkalinity as mg/L CaCO₃ from titrant volume and normality

Sample vol. (mL)

Titrant vol. (mL)

Titrant N (equiv/L)

Chemical Dosing

Dose (mg/L or g/L) from target concentration and volume

Volume (L)

Target conc. (mg/L)

ABV (Alcohol by Volume)

Simple: ABV ≈ (OG − FG) × 131.25 (OG/FG as specific gravity)

OG (specific gravity)

FG (specific gravity)

Sugar Concentration (Brix / Plato)

Brix ≈ Plato for dilute solutions; % sucrose by mass

Brix (°Bx)

Plato (°P)

Alcohol Dilution Calculator

Dilute spirit to target ABV: how much water (or diluent) to add

Spirit volume (ml)

Spirit ABV (%)

Target ABV (%)

Beam Deflection

Simply supported beam with center point load or uniform load → max deflection

Load type

Span length L (m)

Modulus E (GPa)

Moment of inertia I (m⁴)

Point load P (kN)

Uniform load w (kN/m)

Formula: Point load: δ = PL³/(48EI); Uniform: δ = 5wL⁴/(384EI)

Stress & Strain

Force and area → stress; length change → strain and approximate modulus

Force (kN)

Area (mm²)

Original length (mm)

Change in length (mm)

Formula: σ = F/A (stress); ε = ΔL/L₀ (strain); E = σ/ε (modulus)

Bending Moment Calculator

Force × perpendicular distance → bending moment (M = F·d). Supports N, kN, lbf, kip and m, mm, ft, in.

Force

Force unit

Perpendicular distance

Distance unit

Formula: M = F × d (bending moment)

Load Converter

Convert between force/load units: newton (N), kilonewton (kN), pound-force (lbf), kip

Force (N)

Force (kN)

Force (lbf)

Force (kip)

Enter exactly one value; the others will be calculated.

Column Buckling & Load Capacity

Slenderness ratio, end conditions, Euler buckling load, and safety factor → capacity check and failure mode warning

Unbraced length L (in)

End condition factor K

Cross-section area A (in²)

Radius of gyration r (in)

Material

Applied axial load P (lb)

Safety factor

Formula: P_cr = π² E I / (K·L)²; λ = K·L / r

Retaining Wall Stability Simulator

Active earth pressure, sliding and overturning checks, bearing pressure, optional water table

Wall height H (ft)

Base width B (ft)

Stem thickness (ft)

Base thickness (ft)

Toe width (ft)

Backfill unit weight γ (pcf)

Friction angle φ (°)

Wall concrete γ (pcf)

Base friction coeff. μ

Allowable bearing q_a (psf)

Water table depth below top (ft)

Structural Project Risk Analyzer

Load uncertainty, safety factor sensitivity, material cost volatility, and code compliance → risk rating

Load uncertainty

Nominal load uncertainty ± (%)

Load increase scenario (%)

Safety factor sensitivity

Design safety factor (nominal)

Minimum acceptable SF

Material cost volatility

Material cost uncertainty ± (%)

Base material cost ($)

Code compliance flags

Moment of Inertia

Common shapes (rectangle, circle, hollow circle) → second moment of area

Shape

Width b (mm)

Height h (mm)

Thermal Expansion

Length, coefficient, and temperature change → change in length and new length

Initial length (m)

Coefficient α (µm/m·°C)

ΔT (°C)

Fluid Flow

Pipe diameter with either flow rate or velocity → solve the other

Pipe inside diameter (mm)

Flow rate (L/s)

Velocity (m/s)

Provide diameter and at least one of flow rate or velocity; the other will be calculated.

Atmospheric Calculator

All-in-one atmospheric calculator: dew point, humidity, heat index, wind chill, LCL, wet bulb, air density, and density altitude with documented approximations.

°C °F

Air temperature

Relative humidity (%)

Dew point

Wind speed (mph)

Station pressure (inHg)

Sea-level pressure (inHg)

Pressure altitude (ft), optional

Formulas follow common textbook and NWS-style approximations; local terrain, radiation, and instrument errors are not modeled.

Psychrometric Calculator

Psychrometric summary: dew point, mixing ratio, vapor pressures, wet bulb, virtual temperature, θ and θe in one table.

°C °F

Dry-bulb temperature

Relative humidity (%)

Total pressure (inHg)

RH = 0% leaves dew point undefined in this model; other rows still compute.

Open full atmospheric calculator →

Dew Point Calculator

Dew point calculator: convert between dew point, relative humidity, and temperature in °F or °C using a Magnus–Tetens vapor approximation.

Assumes flat equilibrium over liquid water; frost or ice crystals can shift real dew points slightly.

Open full atmospheric calculator →

Vapor Pressure Calculator

Vapor pressure calculator: saturation from temperature, actual from RH, or from dew point (Magnus–Tetens).

Pressures in hPa (mb) and Pa where shown.

Open full atmospheric calculator →

Mixing Ratio Calculator

Mixing ratio calculator from temperature, relative humidity, and pressure in inHg or hPa.

°C °F

inHg hPa

Temperature

Relative humidity (%)

Pressure (inHg)

Assumes ideal gas and liquid-water equilibrium for saturation.

Open full atmospheric calculator →

Virtual Temperature Calculator

Virtual temperature calculator from dry-bulb, relative humidity, and pressure (moist-air ideal gas).

°C °F

Dry-bulb temperature

Relative humidity (%)

Station pressure (inHg)

Small deviations vs radiosonde equations are normal; this is a compact form.

Open full atmospheric calculator →

Equivalent Potential Temperature Calculator

θe calculator: approximate equivalent potential temperature from temperature, humidity, and pressure for meteorology study.

°C °F

Dry-bulb temperature

Relative humidity (%)

Total pressure (inHg)

Not for operational forecasting or storm decision-making without soundings and official data.

Open full atmospheric calculator →

Wet Bulb Calculator

Wet-bulb temperature calculator from dry-bulb, relative humidity, and station pressure using a standard psychrometric solve.

°C °F

Dry-bulb temperature

Relative humidity (%)

Station pressure (inHg)

Natural wet-bulb in extreme heat may differ from this idealized ventilated-bulb model.

Open full atmospheric calculator →

Heat Index Calculator

Heat index calculator from air temperature and humidity. Uses NWS-style regression in the warm band with conservative interpretation text.

°F °C

Air temperature

Relative humidity (%)

Official NWS tables can apply additional rounding; use this as an estimate.

Open full atmospheric calculator →

Wind Chill Calculator

Wind chill calculator using the NWS 2001 formula where applicable, with mph wind speed and °F/°C air temperature.

°F °C

Air temperature

Wind speed (mph)

Clothing, moisture, and sunshine change perceived cold; this is a standardized estimate only.

Open full atmospheric calculator →

LCL / Cloud Base Calculator

LCL calculator: estimate lifting condensation level (cloud base height) in feet and meters from surface temperature and dew point.

°C °F

Temperature

Dew point

Storm chasing and aviation require real soundings and official products. Use this only as a quick sanity check.

Open full atmospheric calculator →

Air Density Calculator

Air density calculator: moist-air density from temperature, pressure (inHg or hPa), and relative humidity or dew point.

Does not model compressibility at extreme altitudes or non-ideal gas corrections.

Open full atmospheric calculator →

Pressure Altitude Calculator

Pressure altitude calculator from station pressure and sea-level / altimeter setting (ISA hypsometric).

Station pressure (inHg)

Sea-level pressure / altimeter setting (inHg)

Use official altimetry and procedures for flight; this is a study aid.

Open full atmospheric calculator →

Density Altitude Calculator

Density altitude calculator from pressure altitude or station pressure plus sea-level pressure and outside air temperature.

Pressure altitude Station + sea-level pressure

°C °F

Pressure altitude (ft)

Outside air temperature

Humidity tweaks to density altitude are small and omitted here for clarity; add a safety margin operationally.

Open full atmospheric calculator →

Lightning Distance Calculator

Lightning distance calculator from flash-to-bang time using speed of sound; miles, km, feet, and meters.

Seconds between flash and thunder

Air temperature (°C) for sound speed

If you can hear thunder, you can be struck. Seek shelter immediately. This tool is not a safety guarantee.

Open full atmospheric calculator →

Acceleration

a = Δv / Δt. Enter two to find the third

Acceleration (m/s²)

Change in velocity Δv (m/s)

Time Δt (s)

Formula: a = Δv / Δt

Stopping Distance

Reaction distance + braking distance = total stopping distance

Speed (km/h)

Reaction time (s)

Deceleration (m/s²)

Formula: Reaction d = v×t; Braking d = v²/(2a); Total = reaction + braking

Free Fall

Time, velocity, and height. Enter two to find the third (g = 9.81 m/s²)

Height h (m)

Time t (s)

Impact velocity v (m/s)

Formula: v = √(2gh); t = √(2h/g); h = ½gt²

Projectile Motion

Initial speed and launch angle → range, max height, flight time (g = 9.81 m/s²)

Initial speed v₀ (m/s)

Launch angle θ (°)

Formula: R = v₀² sin(2θ)/g; H = v₀² sin²θ/(2g); T = 2v₀ sinθ/g

Force (F = ma)

Force, mass, acceleration. Enter two to find the third

Force F (N)

Mass m (kg)

Acceleration a (m/s²)

Formula: F = m × a

Weight

W = m × g (default g = 9.81 m/s²)

Mass m (kg)

g (m/s²)

Formula: W = m × g

Kinetic Energy

KE = ½mv². Enter two to find the third

KE (J)

Mass m (kg)

Speed v (m/s)

Formula: KE = ½ m v²

Potential Energy

PE = mgh. Enter two to find the third (g = 9.81 m/s²)

PE (J)

Mass m (kg)

Height h (m)

g (m/s²)

Formula: PE = m × g × h

Work

W = F × d (force along displacement). Enter two to find the third

Work W (J)

Force F (N)

Distance d (m)

Formula: W = F × d

Hydrostatic Pressure

P = ρgh: pressure at depth (liquid)

Density ρ (kg/m³)

Depth h (m)

g (m/s²)

Formula: P = ρ × g × h

Buoyancy

F_b = ρ_fluid × V × g: buoyant force on submerged volume

Fluid density ρ (kg/m³)

Submerged volume V (m³)

g (m/s²)

Formula: F_b = ρ × V × g

Heat Energy

Q = mcΔT: heat to change temperature

Heat Q (J)

Mass m (kg)

Specific heat c (J/(kg·K))

ΔT (K or °C)

Formula: Q = m × c × ΔT

Wave Equation

v = f × λ. Speed, frequency, wavelength (enter two to find the third)

Speed v (m/s)

Frequency f (Hz)

Wavelength λ (m)

Formula: v = f × λ

Centripetal Force

F = mv²/r (or F = mω²r): force for circular motion

Force F (N)

Mass m (kg)

Speed v (m/s)

Radius r (m)

Formula: F = m v² / r

Friction Force

F_f = μ × N: sliding friction

Friction force F_f (N)

Coefficient μ

Normal force N (N)

Formula: F_f = μ × N

Momentum

p = mv. Enter two to find the third

Momentum p (kg·m/s)

Mass m (kg)

Velocity v (m/s)

Formula: p = m × v

Efficiency

η = (useful output / input) × 100%

Useful output (same units as input)

Input (energy, work, power)

Formula: η = (output / input) × 100%

Load & Demand

Connected loads and demand factor → service load and estimated service current (approximate)

System

Demand factor (%)

Lighting load (kVA)

Receptacles (kVA)

Fixed appliances (kVA)

HVAC / mechanical (kVA)

Other loads (kVA)

For NEC-compliant designs, always verify against the actual code tables for your occupancy and jurisdiction.

Service Load Calculation Engine (NEC)

Residential & small commercial: demand factors, continuous vs non-continuous, EV, generator interlock, 200A/400A recommendation.

System

Service type

General loads (VA)

General lighting

Lighting demand factor (%)

Receptacles (VA)

Receptacle demand factor (%)

Appliances & HVAC

Fixed appliances (VA)

HVAC / mechanical (VA)

HVAC continuous (3+ hrs)

Other loads (VA)

Optional

EV charger (VA)

Generator interlock (exclude from service size)

Code reference: NEC Art. 220. Verify against current code and jurisdiction.

Arc Flash Risk Estimator

Fault current from transformer; working distance → simplified incident energy and PPE category suggestion.

System

Transformer size (kVA)

Secondary voltage (V)

Impedance (%Z)

Working distance (mm)

Simplified estimator. For compliance use dedicated arc-flash study software.

Panel Schedule Builder

Build a panel schedule: breakers, phases, neutral load, AFCI/GFCI. Print or copy.

Panel

Panel name

Bus rating (A)

Breakers

Circuit

Amps

Phase

AFCI

GFCI

Circuit

Amps

Phase

AFCI

GFCI

Generator backfeed circuit

Conduit Fill & Derating

Mixed sizes, THHN/XHHW, ambient & bundling correction, max fill, conduit recommendation.

Ambient temp (°C)

Conductors in cable/conduit

Conduit ID (mm)

Type

Conductor A₁ (AWG or mm²)

Quantity n₁

Conductor A₂

Quantity n₂

Conductor A₃

Quantity n₃

NEC max fill: 53% (1), 31% (2), 40% (3+). Derating per 310.15(B).

Lighting Design

Simple lumen method: room area, target illuminance, and fixture lumens → number of luminaires

Room length (m)

Room width (m)

Target illuminance (lux)

Lumens per fixture

CU (0–1)

LLF (0–1)

Cable Pulling Tension

Total pull tension and bend radius → sidewall bearing pressure

Pull tension T (lb)

Bend radius R (ft)

Allowable sidewall (lb/ft)

Material Takeoff & Cost

Up to three line items → extended cost and total (quick estimating aid)

Item 1 description

Qty 1

Unit cost 1 ($)

Item 2 description

Qty 2

Unit cost 2 ($)

Item 3 description

Qty 3

Unit cost 3 ($)

Electrical Job Cost & Margin

Labor rate, material cost, overhead, profit margin → price to charge. Quote comparison mode.

Labor

Labor rate ($/hr)

Estimated hours

Materials & overhead

Material cost ($)

Overhead allocation (%)

Margin

Target profit margin (%)

Quote comparison (optional)

Quote A price ($)

Quote B price ($)

Code Cross-Reference

Organize code sections for a project and quickly highlight matches (does not contain code text)

Sections (comma- or line-separated)

Search term (optional)

Water Pipe Sizing

Flow, length, and limits → recommended nominal size (using Hazen–Williams approximation)

Flow rate (L/s)

Equivalent length (m)

Allowable head loss (m)

Max velocity (m/s)

Hazen–Williams C

Rule-of-thumb sizing only. For critical systems, verify against local plumbing code tables.

Gas Pipe Sizing

Flow and velocity limit → approximate nominal gas pipe size (velocity-based)

Gas type

Flow rate (m³/h)

Max velocity (m/s)

Uses simple velocity-based sizing. Always confirm with official gas-sizing tables for your code and pressure range.

Drain, Waste & Vent (DWV)

Total fixture units and slope → rule-of-thumb horizontal branch and building drain sizes

Total fixture units

Horizontal slope

Sizing is approximate and for quick checks only. Confirm with your plumbing code (e.g. IPC or UPC) tables for occupancy and fixture mix.

Pressure Loss

Water line diameter, length, and flow → velocity and friction loss (Hazen–Williams)

Pipe diameter (mm)

Equivalent length (m)

Flow rate (L/s)

Hazen–Williams C

Pump Curve Analyzer

Required vs. pump BEP flow/head → simple match index (for quick screening only)

Required flow (m³/h)

Required head (m)

Pump BEP flow (m³/h)

Pump BEP head (m)

Fixture Unit Summary & Layout

Up to four fixture types → total fixture units and suggested building drain size (rule-of-thumb)

Fixture 1 name

Qty 1

FU each 1

Fixture 2 name

Qty 2

FU each 2

Fixture 3 name

Qty 3

FU each 3

Fixture 4 name

Qty 4

FU each 4

Pipe Sizing Engine

Fixture units, material, and run → design flow, velocity check, and smallest pipe that meets limits (conceptual)

Total fixture units

Building type

Pipe material

Equivalent run length (ft)

Allowable friction loss (psi)

Max velocity (m/s)

Uses a simplified demand factor model and Hazen–Williams. For permit work, verify against your plumbing code’s sizing tables.

Water Pressure Drop Planner

Up to three pipe segments + elevation → friction loss, static loss, and booster pump suggestion

Design flow (L/s)

Hazen–Williams C

Water temperature (°C)

Segment 1 length (m)

Segment 1 diameter (mm)

Segment 2 length (m)

Segment 2 diameter (mm)

Segment 3 length (m)

Segment 3 diameter (mm)

Elevation rise (m)

Supply pressure (psi)

Minimum pressure at remote (psi)

Tool is approximate and assumes full-flow Hazen–Williams behavior. Always verify with detailed design calculations.

Drainage & Vent Stack Planner

Fixture units, slope, and trap arms → suggested branch/stack sizes and code-style checks (conceptual)

Branch fixture units (FU)

Total stack fixture units (all floors)

Horizontal branch run (ft)

Horizontal branch slope (% grade)

Trap arm size (in)

Trap arm length (ft)

Vent pipe size (in)

Height of highest fixture (ft)

Uses generic IPC/UPC-style rules of thumb. Always confirm layout and sizing with your local plumbing code.

Tankless Water Heater Sizing

Simultaneous fixtures, inlet temperature, and climate → required GPM and BTU/hr

Climate

Inlet water temp (°F)

Setpoint temp (°F)

Simultaneous fixtures

Showers (2.5 GPM each)

Sinks (1.0 GPM each)

Other hot outlets (GPM)

Assumes typical low‑flow fixtures. For exact sizing, use manufacturer charts for your model and gas type.

Plumbing Job Estimator

Materials, labor, overhead, margin, and emergency markup → recommended quote and profit

Base costs

Materials subtotal ($)

Labor hours

Labor rate ($/hr)

Overhead (% of direct)

Target profit margin (%)

Emergency / after‑hours

Emergency service?

Emergency markup (%)

GPM & LPM Converter

Convert between gallons per minute, liters per minute, and cubic meters per hour

Flow (GPM)

Flow (LPM)

Flow (m³/h)

Enter exactly one value; the others will be calculated.

Water Pressure Converter

Convert between psi, bar, kPa, and meters of water column

Pressure (psi)

Pressure (bar)

Pressure (kPa)

Head (m of water)

Enter exactly one value; the others will be calculated. Uses standard freshwater approximations.

Drain Slope Calculator

Any two of run, drop, and slope → compute the third for basic drain layout

Run (ft)

Drop (in)

Slope (% grade)

Enter any two values; the third will be calculated. Positive slope means flowing “downhill.”

Tank Volume Calculator

Rectangular or cylindrical tank dimensions and fill height → volume in ft³, gallons, and liters

Tank shape

Length (ft)

Width (ft)

Diameter (ft)

Fill height (ft)

Battery Life

mAh, voltage, and load → hours of use

Capacity (mAh)

Voltage (V)

Load (mA or W)

Load unit

Voltage Drop

Approximate voltage drop and % for a copper run

System voltage (V)

Load current (A)

One-way length (ft)

Phase

Wire size (AWG, Cu)

Advanced Voltage Drop Planner

Multi-segment runs, Cu/Al, temperature, parallel conductors, motor surge, cost comparison, optimize for <3%.

System voltage (V)

Load current (A)

Max drop (%)

Conductor

Ambient temp (°C)

Parallel conductors

Segment 1 length (ft)

Segment 2 length (ft)

Motor startup surge (×)

Mode

Wire size (AWG)

Wire Size

Suggest minimum AWG for a circuit based on length, current, and allowed voltage drop

System voltage (V)

Load current (A)

One-way length (ft)

Max voltage drop (%)

Power Calculator

Single- or three-phase: voltage, current, power factor → kW, kVA, and kVAR

Phase

Voltage (V)

Current (A)

Power factor

Electricity Cost

Power, usage hours, and rate → kWh and cost per day, month, and year

Power (W)

Hours per day

Rate ($/kWh)

Battery Backup Calculator

kWh needed to cover a load for a given outage duration (with optional reserve)

Load (kW)

Outage duration (hours)

Reserve margin (%)

Generator & Backup Power Sizing

Whole-home loads, startup surge, fuel type, transfer switch, runtime. Residential & light commercial.

Load (kW)

Safety margin (%)

Startup surge (× running)

Fuel

Tank size (gal), propane/diesel

Transfer switch

Torque Calculator

Power and speed → torque (or use torque and speed to get power)

Power (kW)

Speed (RPM)

Bolt Torque

Preload, diameter, and K-factor → tightening torque

Bolt diameter (mm)

Preload (kN)

K-factor

Gear Ratio

Driver and driven teeth (or speeds) → gear ratio and speed change

Driver teeth

Driven teeth

Input speed (RPM, optional)

Motor Speed

Line frequency, poles, and slip → synchronous and running RPM

Line frequency (Hz)

Poles

Slip (%)

Solar Panel / Savings

System size, tilt factor, sun hours, and rate → daily, monthly, and yearly kWh and bill savings

System size (kW)

Sun hours per day

Tilt factor (optional)

System efficiency (%)

Rate ($/kWh)

Roof Angle / Tilt Calculator

Roof pitch or latitude → tilt angle, tilt factor, and seasonal bias notes

Latitude (°)

Roof pitch (rise:run, e.g. 4:12)

Season focus

Sun Hours by Location

Latitude and climate band → approximate average peak sun hours per day

Latitude (°)

Climate

kWh & Watts Converter

Any two of power, energy, and hours → compute the third

Power (W)

Energy (kWh)

Time (hours)

Enter any two values; the third will be calculated.

Solar System Sizing Engine (Residential)

Monthly usage, climate, roof orientation, and losses → required DC size, panel count, and 20‑year production curve (conceptual)

Average monthly usage (kWh)

Net metering

Climate zone

Roof orientation

Roof tilt (°)

Panel efficiency (%)

Panel rating (W each)

Shading loss (%)

Inverter efficiency (%)

Annual degradation (%/yr)

Solar ROI & Financial Simulator

System cost, incentives, escalation, and financing → payback, NPV, and IRR (conceptual)

Net system cost before incentives ($)

Annual production (kWh)

Current utility rate ($/kWh)

ITC / tax credit (%)

State/local incentives ($)

Utility rate escalation (%/yr)

Analysis horizon (years)

Discount rate (%/yr)

Loan scenario (optional)

Loan APR (%/yr)

Loan term (years)

Lease scenario (optional)

Lease payment ($/month)

Battery Storage Sizing Tool

Critical loads, outage duration, chemistry, and generator → recommended kWh and module count (conceptual)

Average critical load (kW)

Peak critical load (kW)

Outage duration (hours)

Battery chemistry

Depth of discharge limit (%)

Round‑trip efficiency (%)

Generator support (kW, optional)

Battery module size (kWh each)

The optimizer also reports the minimum battery size to cover a 12‑hour outage at the entered average load.

Solar Array Layout Planner

Roof dimensions, panel size, spacing, and obstacles → estimated rows, strings, and layout summary (conceptual)

Roof length (ft, ridge to eave)

Roof width (ft)

Edge & ridge margin (ft)

Panel length (ft)

Panel width (ft)

Row spacing (ft)

Obstruction fraction (% of area)

Modules per string (target)

Module Vmp (V)

Inverter MPPT window (Vmin–Vmax)

Assumes portrait orientation and simple rectangular roof. For permit drawings, use full layout tools and manufacturer requirements.

Commercial Solar Feasibility Tool

Demand charges, TOU rates, incentives, and depreciation → annual savings and simple cash‑flow view (conceptual)

System cost before incentives ($)

Annual solar production (kWh)

On‑peak rate ($/kWh)

Off‑peak rate ($/kWh)

Demand charge ($/kW‑mo)

Demand reduction (kW)

Fraction of solar on‑peak (%)

ITC / tax credit (%)

Bonus + MACRS depreciation years

Corporate tax rate (%)

Analysis horizon (years)

Discount rate (%/yr)

Solar + EV + Battery Integration Planner

EV charging, home battery, and solar → annual energy flows, self‑consumption, and autonomy (conceptual)

Annual solar production (kWh)

Home base load (kWh/year)

EV charging

EV daily miles

EV efficiency (kWh/100 mi)

Charging on solar window (% of kWh)

Battery

Battery size (usable kWh)

Round‑trip efficiency (%)

Target off‑grid autonomy (hours)

Rates & net metering

Utility rate ($/kWh)

Net metering credit (% of retail)

Resistor Color Code

4-band or 5-band → resistance and tolerance

Bands

1st

2nd

Multiplier

Tolerance

Capacitor Code

Code → capacitance (pF, nF, µF). Supports 3-digit (e.g. 104), letter suffix (10n, 22p, 4u7)

Code

Break-Even

Fixed cost, variable cost, price → break-even units and revenue

Fixed Cost ($)

Variable Cost per Unit ($)

Price per Unit ($)

Cost & Revenue vs Units

Margin vs Markup

Convert between margin % and markup %; cost and sell price

Cost ($)

Sell Price ($)

Area & FAR

Lot area, footprint, and floors → floor area ratio (FAR)

Lot Area (sq ft)

Building Footprint (sq ft)

Number of Floors

Occupancy Load

Area and load factor → maximum occupants

Floor Area

Area Unit

Load Factor (area per person)

Factor Unit

Ramp Slope

Rise and run → slope percent and ratio

Rise

Run

Unit

Sun Angle & Shadow

Any two of height, sun angle, or shadow length → solve the third

Height

Shadow Length

Sun Angle (°)

Enter any two values; the third will be calculated. Use consistent units for height and shadow.

Concrete

Slab length, width, and thickness → volume and bag count

Length (ft)

Width (ft)

Thickness (in)

Tile

Room size and tile size → tiles needed (with waste)

Room Length (ft)

Room Width (ft)

Tile Length (in)

Tile Width (in)

Waste (%)

Paint

Room dimensions and coats → gallons of paint

Room Length (ft)

Room Width (ft)

Ceiling Height (ft)

Number of Coats

Coverage (sq ft/gal)

Flooring

Room area and waste → total flooring needed

Room Length (ft)

Room Width (ft)

Waste (%)

Stair Design

Total rise and run → number of steps and dimensions

Total Rise (in)

Total Run (in)

Square Footage

Length and width → area in sq ft and sq m

Length (ft)

Width (ft)

Gravel

Area and depth → gravel volume and tons

Length (ft)

Width (ft)

Depth (in)

Mulch

Beds area and depth → mulch cubic yards and bags

Length (ft)

Width (ft)

Depth (in)

Roofing

Roof size and pitch → squares and bundles

Roof Length (ft)

Roof Width (ft)

Pitch Factor

Roofing Material Optimizer

Roof geometry, complexity, and productivity → shingles, underlayment, fasteners, and labor estimate

Roof Length (ft)

Roof Width (ft)

Pitch factor

Roof complexity

Extra waste (%)

Underlayment coverage (ft²/roll)

Fasteners per square

Squares per crew‑day

Crew size

Deck

Deck size → area and board count (approximate)

Deck Length (ft)

Deck Width (ft)

Board Width (in)

Framing Layout Optimizer

Wall length, stud spacing, and openings → studs, waste, and cost estimate

Wall length (ft)

Stud spacing (in)

Stud height (ft)

Opening 1 width (ft, optional)

Opening 2 width (ft, optional)

Opening 3 width (ft, optional)

Waste (%)

Cost per stud ($)

Slab Thickness & Reinforcement Estimator

Uniform load, f′c, slab size → suggested thickness, deflection estimate, rebar spacing suggestion, and takeoff

Design inputs

Slab length (ft)

Slab width (ft)

Thickness (in)

Concrete f′c (psi)

Uniform load (psf, total)

Reinforcement

Mix ratio (cement:sand:aggregate)

Rebar size

Rebar spacing (in, each way)

Suggested thickness from span/depth; deflection from one-way strip. Confirm with project specs and codes.

Concrete Pour Planner

Slab, waste, trucks, reinforcement, cost, crew, and cure milestones in one view

Slab length (ft)

Slab width (ft)

Thickness (in)

Waste factor (%)

Truck capacity (yd³)

Concrete cost ($/yd³)

Rebar weight (lb/yd³)

Rebar cost ($/lb)

Crew size

Productivity (yd³/crew‑hr)

Hours per day

Structural Load

Uniform floor/roof load, span, and spacing → line load, reactions, and max moment/shear (for checking against tables)

Design load (psf)

Span (ft)

Joist spacing (in)

Results are for simple spans with uniform load. Use official span tables or an engineer for final sizing.

Beam Load & Deflection Engine

Multiple support types, uniform and point loads, wood/steel/concrete, deflection limits (L/240–L/480), pass/fail, minimum beam size

Support type

Material

Span (ft)

Uniform load (plf)

Point load P1 (lb)

P1 position from left (ft)

Point load P2 (lb)

P2 position from left (ft)

Beam width b (in)

Beam depth d (in)

Allowable bending stress Fb (psi)

Deflection limit

Safety factor

Footing & Soil Bearing Planner

Total load, soil bearing, footing size, safety margin, and settlement estimate

Total factored load (kips)

Support type

Soil bearing capacity (psf)

Number of columns

Proposed footing width (ft, optional)

Wall length (ft)

Proposed footing width (ft, optional)

Safety factor

Soil modulus E_s (ksf, for settlement)

Poisson ratio ν (optional)

Earthwork / Cut & Fill

Area and average cut/fill depths → volumes in cubic yards and net balance

Area Length (ft)

Area Width (ft)

Average cut depth (ft)

Average fill depth (ft)

Rebar Weight & Spacing

Bar size, length, and spacing → total weight and number of bars

Bar size (#)

Length per bar (ft)

Number of bars

Spacing (in), optional

Span length (ft), if using spacing

Soil Compaction Calculator

Field density and moisture → dry density, % compaction (relative to max dry density)

Wet (field) density (lb/ft³)

Moisture content (%)

Max dry density (lb/ft³), lab

Asphalt Tonnage Estimator

Area, thickness, and density → tons of asphalt needed

Area (ft²)

Thickness (in)

Density (lb/ft³)

Drainage Flow Rate

Manning formula: slope, area, hydraulic radius → flow (open channel)

Cross-section area (ft²)

Wetted perimeter (ft)

Slope (ft/ft)

Manning n

Steel Beam Weight

Section weight per foot × length → total weight (A36 steel)

Weight per foot (lb/ft)

Length (ft)

Quantity

Section Modulus Calculator

Rectangular section: width × depth → S = bd²/6 (in³ or mm³)

Width b (in)

Depth d (in)

Bolt Shear & Tensile Capacity

Bolt diameter and material → approximate shear and tensile capacity (A325/A490)

Bolt diameter (in)

Grade

Thread condition

Three-Phase Power Calculator

kW ↔ amps, line voltage, power factor (3-phase)

Solve for

Line voltage (V)

Power factor

kW

Amps

Transformer Sizing

Load kVA or kW (with PF) → recommended transformer kVA

Load (kW)

Power factor

Safety margin (%)

Power Factor Correction

Current PF and target PF → reactive kVAR and capacitor size

Real power (kW)

Current PF

Target PF

Pump Horsepower Calculator

Flow (GPM), head (ft), and efficiency → brake horsepower

Flow (GPM)

Head (ft)

Efficiency (%)

Land Area (Irregular Polygon)

Shoelace formula: enter coordinates (ft or m) → area

Enter vertices in order (e.g. N, E or X, Y). One point per line: x,y (e.g. 0,0 then 100,0 then 100,50 then 0,50)

Coordinates (x,y one per line)

Slope Distance Calculator

Horizontal distance and elevation change → slope distance and grade %

Horizontal distance (ft)

Elevation change (ft)

Reynolds Number Calculator

Re = ρVD/μ: pipe flow (diameter, velocity, density, viscosity)

Diameter (in)

Velocity (ft/s)

Density (lb/ft³)

Viscosity (lb/(ft·s))

Pipe Pressure Drop (Gas)

Simplified: flow, pipe size, length → pressure drop (Darcy-Weisbach style)

Flow rate (SCFM or ft³/min)

Pipe ID (in)

Length (ft)

Friction factor f (approx)

Flow Velocity in Pipe

Flow rate and pipe diameter → velocity (ft/s or m/s)

Flow (GPM)

Pipe ID (in)

Fiber Link Budget Calculator

Transmit power, cable loss, splices, connectors → received power and margin

Tx power (dBm)

Cable loss (dB/km)

Distance (km)

Splice count

Loss per splice (dB)

Connector pairs

Loss per pair (dB)

Rx sensitivity (dBm)

Signal Loss / Attenuation

Loss per unit length × distance → total dB loss

Attenuation (dB/km)

Distance (km)

Additional loss (dB), splices, connectors

Thermal / HVAC Load

Rule-of-thumb heating & cooling load from area, height, and insulation level

Conditioned floor area (ft²)

Ceiling height (ft)

ΔT (indoor–outdoor, °F)

Insulation level

Approximate “block load” only. For detailed HVAC design, use full Manual J / ASHRAE methods.

Room BTU Calculator

Single room dimensions and insulation → recommended heating & cooling BTU/hr

Room length (ft)

Room width (ft)

Ceiling height (ft)

ΔT (indoor–outdoor, °F)

Insulation level

CFM Calculator

Room volume and target air changes per hour → required supply airflow (CFM)

Room length (ft)

Room width (ft)

Ceiling height (ft)

Target ACH (air changes/hr)

Supply registers (optional)

Air Changes Per Hour

Measured airflow and room size → air changes per hour (ACH)

Room length (ft)

Room width (ft)

Ceiling height (ft)

Supply airflow (CFM)

SEER Savings Estimator

Existing vs new SEER, usage, and rate → annual energy savings and simple payback

Cooling capacity (BTU/hr)

Cooling hours per year

Existing SEER

New SEER

Electricity rate ($/kWh)

Upgrade cost difference ($, optional)

Heat Load Engine (Manual J Simplified)

Floor area, envelope, windows, and climate → estimated heating & cooling BTU/hr and equipment size (conceptual)

Conditioned floor area (ft²)

Ceiling height (ft)

Climate zone

Wall insulation

Window area (% of floor)

Window orientation

Home tightness

Occupants

Equipment / plug load (BTU/hr)

Conceptual sizing only. For permit or code‑critical designs, use full Manual J or local engineering standards.

Duct Sizing Planner

Target airflow, length, and friction rate → suggested duct size, velocity, and static margin (conceptual)

Total airflow (CFM)

Main duct length (ft)

Design friction rate (in w.c./100 ft)

Available static pressure (in w.c.)

Preferred velocity band

Duct shape

Rectangular aspect ratio (W:H)

HVAC System Cost & ROI Simulator

Existing vs upgrade system (cooling + heating) → annual cost, lifetime cost, and simple payback

System capacity (tons)

Cooling hours per year

Heating hours per year

Electricity rate ($/kWh)

Gas rate ($/therm)

Existing system

Existing SEER

Existing furnace AFUE (%)

Upgrade scenario

Upgrade type

New SEER

Heat pump heating COP (if applicable)

Analysis horizon (years)

Upgrade cost difference ($)

Refrigerant Line Sizing

Tonnage, line length, and rise → equivalent length, capacity impact, and oil return risk (conceptual)

System capacity (tons)

Suction line length (ft)

Liquid line length (ft)

Vertical rise (ft, outdoor unit above indoor)

Base allowable length (ft, per mfr)

HVAC Quote Builder

Equipment, labor, overhead, and financing → customer price, margin, and monthly payment

Costs

Equipment cost ($)

Labor cost ($)

Overhead (% of direct)

Add‑ons & margin

Warranty & add‑ons ($)

Target profit margin (%)

Financing

APR (% per year)

Term (months)

Down payment ($)

Bill of Materials (BOM)

Quick material list with extended costs and project total

Item description

Qty

Unit cost ($)

Item description

Qty

Unit cost ($)

Item description

Qty

Unit cost ($)

Labor Burden & Productivity

Crew size, wage, burden, and productivity → daily and total labor cost and cost per unit

Crew size

Base wage ($/hr per person)

Burden factor (%)

Hours per day

Days on job

Productivity (units/crew‑hr)

Project Margin Simulator

Material volatility, labor shifts, and delays → best/worst-case margins and break-even

Base material cost ($)

Base labor cost ($)

Overhead & other ($)

Target profit margin (%)

Material volatility (±%)

Labor volatility (±%)

Potential delay (days)

Carrying cost ($/day)

Schedule / Gantt Export

Any number of tasks → sequential schedule, dates (optional), and CSV-friendly rows

Project start date (optional)

Tasks are treated sequentially. Copy the CSV-style output row into your scheduling or Gantt software.

Task name

Duration (days)

Task name

Duration (days)

Task name

Duration (days)

Construction Bid Comparison

Compare any number of bids with schedule, material normalization, and risk‑weighted cost model

Overhead / carrying cost ($/day)

Bid

Contractor name

Bid price ($)

Schedule (days)

Material pricing vs baseline (%)

Risk score (1–5)

Bid

Contractor name

Bid price ($)

Schedule (days)

Material pricing vs baseline (%)

Risk score (1–5)

Bid

Contractor name

Bid price ($)

Schedule (days)

Material pricing vs baseline (%)

Risk score (1–5)

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GRAPH SYSTEMS OF EQUATIONS (CALCULATOR + INTERACTIVE GRAPH)

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