Free tool
Mortgage amortization calculator with extra payments
Enter a loan amount, rate and term to see the monthly payment and a year-by-year amortization schedule, then add extra payments to see how much sooner the loan is paid off and how much interest you save. Everything stays in your browser — nothing you type is sent or stored.
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How the schedule is worked out
Each month, interest is the current balance times the monthly rate. The rest of the payment reduces the balance. Because interest is charged on a shrinking balance, the interest part falls and the principal part grows every month. Extra payments go straight to principal, so every later month’s interest is a little smaller and the loan finishes sooner.
Check how your servicer applies extra principal and any prepayment penalty before using a payoff plan. CFPB source checked October 8, 2026. Rates and amounts shown are examples, not quotes.
Using it with buyers and homeowners
- Print the plain schedule so a buyer can see how slowly the balance falls in the first years.
- Run an extra $100, $200 and $500 a month and show the years and interest saved.
- Try a one-time lump sum, such as a bonus or tax refund, in a chosen month.
- Remind them to check the loan for prepayment penalties and to ask that extra money be applied to principal.
To focus on total interest and a monthly breakdown, use the mortgage interest calculator. For the full monthly payment with tax, insurance, HOA and PMI use the mortgage payment calculator. Thinking of a new rate? Try the refinance break-even calculator, see equity with the home equity calculator, or check the home affordability calculator. More in the free tools for real estate agents.
Common questions
What is a mortgage amortization schedule?
It is a table showing how each payment on a fixed-rate loan is split between interest and principal, and the balance left after it. Early payments are mostly interest; over time more of each payment goes to principal. The sheet shows the schedule year by year; Download monthly CSV gives every payment for the current scenario.
How is the monthly payment worked out?
With a monthly rate r (the annual rate divided by 12) and n monthly payments, the payment is loan × r ÷ (1 − (1 + r)^−n). At a 0% rate the loan is simply divided by the number of payments.
How much does an extra mortgage payment save?
Extra money paid toward principal reduces the balance sooner, so less interest is charged every month afterwards. Enter a monthly extra amount, a one-time lump sum, or both, and the calculator shows the new payoff time and the interest saved against the normal schedule. Check with the lender that extra payments are applied to principal and that the loan has no prepayment penalty.
What extra mortgage payment reaches my payoff goal?
Enter a target payoff month to estimate the monthly extra on top of the calculated principal-and-interest payment. Apply the suggestion to update the schedule. It assumes the same fixed rate and no one-time extra payment; any lump sum you entered stays in place and may repay the loan sooner. Taxes, insurance, lender rounding and prepayment fees are excluded.
Can I download a monthly amortization spreadsheet?
Yes. Download monthly CSV gives the current scenario’s opening balance, regular principal-and-interest payment, actual monthly and one-time extras, total payment, interest, principal and closing balance for every payment month. Amounts use the selected currency and retain extra decimal places for spreadsheet calculations. No names or contact details are included. It is an estimate, not a lender repayment schedule.
Does this include taxes, insurance or PMI?
No. It covers principal and interest on the loan only. For the full monthly payment with property tax, insurance, HOA and PMI use the mortgage payment calculator.
Is this a loan offer or a quote?
No. It is an estimate built only from the figures you enter, not a loan offer, a Loan Estimate or advice. Actual lender schedules can differ slightly in rounding and in how extra payments are applied.
Does the calculator save what I enter?
No. The amounts, names and contact details stay in your browser and are not sent to Kadapt, stored, or used in analytics. Only button actions are counted, never the entered values or the contents of a download.