An amortization calculator shows how much of each loan payment goes toward principal versus interest, and how your loan balance declines over time.
The principal you're borrowing.
Most commonly 15 or 30 years for a mortgage.
Applied to your remaining balance each period.
When repayment begins — used to map out each future payment.
Applied to principal, shortening the loan and cutting total interest.
Loan paid off in Sep 2056 after 360 payments.
These results are estimates, not predictions. They're calculated from the figures you entered and assume your rate of return and inflation rate hold steady every year, which real markets don't do. Change any input and the result changes. Use this to compare scenarios, not to plan around a specific number.
Enter your loan amount, loan term, interest rate, and start date. You can optionally add extra payments. The calculator shows your monthly payment, total interest paid, total cost of the loan, payoff date, and a month-by-month schedule.
Loan amount is the principal you're borrowing.
Loan term is how long you have to repay the loan, most commonly 15 or 30 years for a mortgage.
Interest rate is applied to your remaining balance each period, so a higher rate increases the portion of each payment that goes toward interest rather than principal.
Loan start date is when repayment begins, which the schedule uses to map out each future payment.
Extra payments applied to principal reduce the balance that future interest is calculated on, which can shorten your loan and reduce total interest paid.
Early payments are interest-heavy, since interest is calculated on a still-large balance. As the balance shrinks, more of each payment shifts toward principal. On a typical 30-year fixed loan, the point where principal outpaces interest in your payment usually doesn't arrive until year 18 or 19. On a 15-year loan, that shift happens by year three or four.
Lenders calculate your monthly principal and interest payment using M = P × [r(1 + r)^n / ((1 + r)^n − 1)], where P is your loan amount, r is your monthly interest rate, and n is your total number of payments. This calculator applies the same formula to build out your full payment-by-payment schedule.
On a $400,000, 30-year loan at 6.10%, the monthly principal and interest payment is about $2,424. After five years, you'll have paid roughly $145,000 total, but reduced your balance by only about $27,000, since the bulk of early payments goes to interest. By year 19, that ratio flips, and most of each payment finally goes toward principal.
This calculator is built for fixed-rate loans, where the rate and payment stay constant for the full term. An adjustable-rate mortgage recalculates its amortization schedule each time the rate resets, using the remaining balance, the new rate, and the years left on the loan, which can shift your payment significantly from what a fixed-rate schedule would show.
A fiduciary financial advisor can help you decide whether extra payments or refinancing make more sense for shortening your amortization timeline. Matching with an advisor is free and comes with no pressure to commit.
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