Mortgage Amortization Schedule Calculator

About this calculator

For a fixed-rate mortgage, the monthly payment is constant but the split between interest and principal shifts every month — this calculator finds that payment using M = P[r(1+r)^n] ÷ [(1+r)^n − 1], where P is the loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of payments. It then shows the first month's breakdown: interest is the outstanding balance times the monthly rate, and principal is simply the payment minus that interest.

Because interest is charged on the remaining balance, early payments are interest-heavy and later payments are principal-heavy — a structure homebuyers comparing loan offers, real-estate agents illustrating equity buildup, and mortgage brokers use to show clients not just the monthly payment but the total interest paid over the life of the loan (often exceeding the original principal on a 30-year term), and how extra principal payments early on can meaningfully shorten that timeline.