Investment Calculator
Quick answer
Pick a mode (lump sum, savings goal, CD, or growth with contributions), enter rate and horizon, then inspect charts and schedules. Treat return and inflation as levers to stress-test, not facts.
For a related estimate, see 401k Calculator.
Explore further: Compound Interest Calculator · Future Value Calculator
Growth building blocks
Future value layers compound returns on prior balance plus new contributions. Frequency matters because interest earns on interest more often when compounded more frequently.
Explore further: Gdp Calculator · Ira Calculator
Investing ties together starting capital, contributions, return assumptions, time, and compounding frequency. This calculator surfaces future value and breakdowns so you can see how much growth vs principal drives the outcome.
How to use this calculator
- Choose the right mode: Lump sum answers “what if I invest once?” Growth with contributions models ongoing saving.
- Set compounding realistically: Monthly compounding differs slightly from annual — match what your scenario assumes.
- Add inflation when comparing goals: Real vs nominal matters for long horizons.
When simple vs compound matters
Simple interest grows linearly; compound interest accelerates when returns stay positive and reinvest. Short horizons look similar; long horizons diverge.
Real-world examples
- Example: steady contributions: Monthly deposits into a balanced return assumption illustrate how contributions and growth split over 20 years — illustrative only.
- Sensitivity check: Nudge the rate by about +0.5% and the principal by about −5%. If the payment, break-even, or target amount moves enough to change your decision, you are still on a steep part of the curve where small inputs matter.
Explore further: Savings Rate Calculator
How to read results
If results rely on high returns, rerun with lower returns to test fragility. If the plan only works at peak assumptions, widen savings or extend the timeline.
FAQ
Are growth projections guaranteed?
No. Returns are uncertain; use ranges and stress tests rather than a single optimistic path.
Should I compare pre-tax and Roth using the same return?
You can, but spendable dollars differ at withdrawal — tax location matters for net outcomes.
How accurate is this calculator?
It applies standard math to the inputs you enter. Real lenders, payroll rules, and rounding can differ—use results for planning and comparison, not as binding quotes.