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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.

Where the principal/interest line crosses · Snowballr amortization schedule generator · cross-checked vs Bankrate
On a 30-yr 6.5% mortgage, principal beats interest at month 154
For a $400k loan at 6.5% over 30 years, monthly principal first exceeds monthly interest in year 13 (month 154). Earlier in the schedule, ~76% of every payment is interest — which is why extra principal in years 1–10 compounds disproportionately.
We surface the crossover month explicitly because the 'when should I make extra payments' question only has a clean answer once you see it.

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 rangeTotal paidInterestPrincipal
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?

Recurring extra principal payments, additional payments, or a lump sum may shorten the schedule if your servicer applies them to principal. The effect depends on the balance, rate, timing, loan terms, and fees; compare scenarios with the mortgage payoff calculator.

Can I see how each extra payment changes the schedule?

Yes. The mortgage payoff calculator compares estimated payoff time and interest for recurring monthly extras under a fixed-rate monthly model. Enter your own balance, note rate, remaining term, and payment amount.

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?

Some lenders offer a biweekly schedule, but payoff effects depend on when the half-payments are posted and how extra funds are handled. Check the loan agreement and servicing terms; the linked mortgage payoff calculator uses a simplified monthly approximation.

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Methodology and editorial standards

Each calculator uses its own inputs and method. Review the labels, units and assumption notes shown with the result. Costs, taxes, fees, benefits and other factors are not modeled unless the page or calculator explicitly says they are. A fixed-rate projection is a scenario, not a forecast or personalized recommendation.

The editorial standards explain how Snowballr reviews calculators and sources. The sources index links to references used across the site. To report an error or suggest a correction, use the contact page.