Free · No sign-up required
Free · Full schedule · Any loan
Amortization calculator
See your loan's complete amortization schedule. Watch interest dominate the early years and principal take over the back half — the math behind every fixed-rate loan.
What is amortization?
Amortization is the schedule of how each fixed monthly payment is split between interest (paid on remaining balance) and principal (paid down on the loan). The payment is constant; the split changes each month.
Early payments: mostly interest because the balance is huge. Late payments: mostly principal because the balance is small. The crossover point on a 30-year mortgage is typically around year 18–20.
$300k mortgage at 7% — first 5 years vs last 5 years
| Year range | Total paid | Interest | Principal |
|---|---|---|---|
| Years 1–5 | $119,724 | $101,470 (85%) | $18,254 (15%) |
| Years 6–10 | $119,724 | $94,672 (79%) | $25,052 (21%) |
| Years 11–15 | $119,724 | $85,343 (71%) | $34,381 (29%) |
| Years 16–20 | $119,724 | $72,538 (61%) | $47,186 (39%) |
| Years 21–25 | $119,724 | $54,963 (46%) | $64,761 (54%) |
| Years 26–30 | $119,724 | $30,841 (26%) | $88,883 (74%) |
Amortization formula
Monthly interest = Balance × (APR / 12) Monthly principal = Payment − Monthly interest New balance = Old balance − Monthly principal Payment = P × r × (1+r)^n / ((1+r)^n − 1) P = principal, r = APR/12, n = months
Amortization Calculator FAQ
Why is most of my mortgage payment going to interest?
Because interest is calculated on the remaining balance. On a 7% 30-year $300k mortgage, the first payment is ~$1,996, of which ~$1,750 is interest and only ~$246 is principal. As you pay down the balance, the interest portion shrinks every month — slowly at first, fast in years 20–30.
What's a fully amortized loan?
A loan where the standard monthly payment fully pays off principal + interest by the end of the term. The opposite is an interest-only loan (no principal reduction until the end) or a negative amortization loan (balance grows). Most mortgages, auto loans, and personal loans are fully amortized.
How can I pay off my mortgage faster?
Extra principal payments. Even one extra payment per year cuts a 30-year mortgage by ~4 years. Bi-weekly payments (26 half-payments = 13 full payments per year) cuts it by ~6 years. Lump sums in early years have the biggest impact because they avoid years of interest.
Can I see how each extra payment changes the schedule?
Yes — try the mortgage payoff calculator for that view. The compounding effect of even small extras is large. $100 extra on a $300k mortgage at 7%: saves ~$84,000 in interest and 6.5 years.
Is amortization the same as depreciation?
No. Amortization is the gradual paydown of a loan principal. Depreciation is the decline in an asset's value over time. They share math (gradual schedule) but refer to opposite things — one's a liability shrinking, the other's an asset losing value.
What if I make biweekly payments?
You make 26 half-payments per year instead of 12 monthly = 13 full payments per year. On a 30-year mortgage that shaves ~6 years off the term. Make sure your lender applies extras to principal (some hold the extra and apply at month-end — slightly less efficient).