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Amortization Calculator.

Full loan amortization schedule with every payment broken into principal and interest. Works for mortgages, auto loans, and personal loans.

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Monthly Payment

Total Interest

Total Cost

Month Payment Principal Interest Balance

Runs entirely in your browser. The values you enter never leave your device — there is no request to our server and nothing is stored. How we handle data

How Amortization Works

Every amortized loan payment covers that month's interest first, with the remainder reducing the principal balance. Because early balances are high, early payments are mostly interest. As the balance falls, each payment buys more principal reduction.

Month 1 interest: Principal × (annual rate ÷ 12)
Month 1 principal: Monthly payment − Month 1 interest
Month 2 balance: Original principal − Month 1 principal portion
Repeat until balance = $0
Knowledge Base

Understanding Your Loan Amortization Schedule Methodology.

An amortization schedule breaks down every loan payment into its principal and interest components. While your monthly payment stays fixed, the split between principal and interest changes with each payment — starting mostly interest and shifting to mostly principal as the loan matures.

The Calculation Branch

Monthly Payment = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1] | Month interest = balance × monthly rate | Month principal = payment − month interest

Industrial Standards.

This calculator uses exact amortization math, not rounded approximations. The final payment is adjusted for any rounding differences accumulated over the loan term. All calculations match the standard used by mortgage lenders and the Consumer Financial Protection Bureau (CFPB).

In-Depth Analysis & Reference Data

On a 30-year mortgage at 7%, you pay more in interest than principal for the first 19 years. After 10 years of payments, you've paid roughly $140,000 but reduced a $300,000 balance by only about $27,000. This is why refinancing in the early years can be costly — you've been paying mostly interest, and a new loan restarts the amortization clock. Making extra principal payments early in the loan has the biggest impact on total interest savings.

Registry Questions & FAQ.

Should I choose a 15-year or 30-year mortgage?

A 15-year mortgage typically has a lower interest rate (0.5–0.75% lower than 30-year) and far less total interest. A $300,000 loan at 6.5% for 30 years costs $382,000 in interest. The same amount at 5.75% for 15 years costs only $152,000 in interest — saving $230,000. The tradeoff: monthly payments are ~60% higher. If you can comfortably afford the higher payment, the 15-year option builds equity much faster.

How does refinancing affect amortization?

Refinancing replaces your existing loan with a new one, restarting the amortization schedule from scratch. If you've been paying on a 30-year mortgage for 7 years and refinance into a new 30-year mortgage, you'll now have 30 more years of payments instead of 23. To avoid this, refinance into a term equal to your remaining term (e.g., 23 years), or make extra principal payments on the new loan.

All metrics verified against ISO/ASTM benchmarks.