Amortization Calculator
See exactly how each monthly payment splits between principal and interest, your remaining balance every year, and total interest paid over the life of your loan. Download the full month-by-month schedule as CSV.
How loan amortization works
An amortization schedule is the month-by-month breakdown of how your fixed monthly payment is split between principal (the loan balance you're paying down) and interest (the lender's fee for lending you the money). Early in the loan, most of your payment goes to interest because the outstanding balance is large. As the balance shrinks, more of each payment goes to principal — eventually leaving you mortgage-free at the final payment.
The monthly payment itself is constant for a fixed-rate loan, calculated using the standard amortization formula: PMT = P × r × (1+r)^n / ((1+r)^n − 1) where P is the original loan amount, r is the monthly interest rate (APR ÷ 12), and n is the total number of monthly payments.
Each month, the calculation is:
- Interest this month = current balance × monthly rate
- Principal this month = monthly payment − interest
- New balance = current balance − principal
For full PITI including property tax and insurance, use the Mortgage Calculator. To see how extra payments shorten the schedule, see the Mortgage Payoff Calculator.