Amortization Schedule Calculator

This tool builds a full amortization schedule for any fixed-rate loan and summarizes it year by year. Enter the principal, the annual interest rate, and the term in years, and it generates the complete month-by-month payoff, then shows one row per year — each row is that year’s final monthly payment split into principal and interest, plus the balance still owed. Watching the interest column shrink while the principal column grows is the clearest picture of how an amortizing loan actually gets repaid.

The fixed payment comes from the standard formula payment = P × r × (1 + r)ⁿ / ((1 + r)ⁿ − 1), where P is the principal, r is the monthly rate (annual rate ÷ 12 ÷ 100), and n is the number of months. The schedule then iterates month by month: interest = balance × r, principal = payment − interest, and the balance drops by that principal portion. Each figure is rounded to the cent, and the final month settles the exact remaining balance so the loan ends at $0.

A fully worked example: $200,000 at 6% for 30 years. The monthly rate is 0.06 ÷ 12 = 0.005 and n = 360, so 1.005³⁶⁰ ≈ 6.0226 and the payment is $1,199.10 per month. In month 1, interest is 200,000 × 0.005 = $1,000.00, leaving just $199.10 for principal and a balance of $199,800.90. By the end of year 1 the split is $988.77 interest to $210.33 principal with $197,543.99 still owed; by the end of year 15 it is $712.92 to $486.18 with a balance of $142,097.98. Principal finally overtakes interest in month 223 — year 19 — and total interest over the full term comes to $231,676.38, more than the amount borrowed.

Two caveats when reading the table. It covers principal and interest only, so property taxes, insurance, and other escrow items on a real mortgage statement are not included. And it assumes you pay exactly the scheduled amount every month — extra principal payments are not modeled, though the schedule makes their appeal obvious: any extra dollar paid early avoids interest at the loan’s rate for every remaining month. Because of cent-by-cent rounding, the last payment differs slightly ($1,200.14 here); lenders true up the final installment the same way.