Amortization Schedule Calculator

Build your amortization schedule

Enter your mortgage details to see a year-by-year breakdown of every payment: how much goes to principal, how much goes to interest, and what you still owe at the end of each year.

How this is calculated

Each year the tool adds up twelve monthly payments (or 26 bi-weekly, or 52 weekly). Within every payment, interest is charged on the outstanding balance first and the remainder reduces the principal. The monthly rate comes from semi-annual compounding: i = (1 + annual rate ÷ 2)^1/6 − 1 for monthly payments, with exponents of 1/13 for bi-weekly and 1/26 for weekly. The fixed payment is P = L × i ÷ (1 − (1 + i)⁻ⁿ), where L is the mortgage amount and n is the total number of payments. At 0% interest the payment is L ÷ n and the schedule is simply the principal divided evenly.

Reading the schedule

Early in the amortization most of each payment is interest and only a small slice reduces the balance. As the balance falls, the interest portion shrinks and the principal portion grows. That is why the closing balance barely moves in the first few years and then drops quickly near the end. The final payment is adjusted so the balance lands exactly at zero.

What changes the schedule

• A lower rate reduces total interest and lets each payment retire principal faster.
• A shorter amortization raises the payment but cuts total interest substantially.
• More frequent payments change the payment size, though regular bi-weekly and weekly schedules produce similar total interest to monthly.
• Prepayments, lump sums, and accelerated payments are not included here and would shorten the schedule.

Why your lender's numbers may differ

Lenders round to the cent, may set the payment slightly higher to guarantee payoff, and may apply different compounding for variable-rate products. Insurance premiums financed into the mortgage and any fees added to the loan also change the balance. Use this schedule for planning, not as a statement of your account.