A $1,800 payment, mostly interest at first
Month one on a typical fixed mortgage: most of your payment is interest, because interest is charged on the whole balance you still owe. That is arithmetic, not a penalty. The same payment later reduces principal by more, because the balance has shrunk.
Why it is worth reading the schedule once
Amortization answers the questions that actually matter: how much will this loan cost in total, where does an extra payment help most, and whether refinancing resets the front-loaded interest profile. Skip the table and you are negotiating without the numbers.
What amortization means in plain terms
A fixed payment loan repays in equal installments, but each installment splits into interest (cost of borrowing what you still owe) and principal (actually reducing debt). Early rows are interest-heavy because the owed balance is large.
How each row is built
- Start with beginning balance for the period.
- Interest piece ≈ balance × periodic rate (match day-count rules your loan uses).
- Principal piece = payment minus interest.
- Ending balance = beginning balance minus principal. Repeat.
Early months: interest dominates (large balance) Later months: principal dominates (smaller balance) Total interest = sum of the interest column: long terms amplify this
Try it yourself
What feels unfair vs what is math
Feeling: “My payment should cut principal now.” Reality: interest = rate × balance, big balance, big interest slice Extra principal payments attack the balance directly: see the next rows change
Where schedules matter
- Mortgages
- Auto loans with level payments.
- Student loans: watch capitalization if payments do not cover accruing interest.
Mistakes
- Calling amortization “interest front-loaded” as if it were moral. It is balance × rate.
- Comparing refinance savings using monthly payment alone without total interest over the years you will keep the loan.
- Ignoring escrow and insurance in household cash flow. They are not “interest,” but they are cash.
Use the calculator
FAQ
- Is amortization the same for ARMs?
Schedules reset when the rate resets; watch adjustment caps and new assumptions.
- Why does my first payment look almost all interest?
Because interest is computed on the full balance. As balance falls, more of each payment goes to principal.
- Does a lump-sum extra payment change the schedule?
Usually yes on the principal path. Verify how your servicer applies prepayments.