What is Loan Amortization?
Loan amortization is the process of paying off a debt through regular scheduled payments over a set period. Each payment covers the interest that has accrued on the outstanding balance plus a portion of the principal. In the early years of a loan, the majority of each payment goes toward interest; over time, the interest portion shrinks and the principal portion grows — until the final payment fully pays off the loan. This gradual paydown schedule is called an amortization schedule.
Understanding amortization helps borrowers make smarter decisions: knowing how much of your $2,000 mortgage payment goes to interest versus principal, how extra payments accelerate payoff, and what your loan truly costs over its lifetime. On a 30-year, $300,000 mortgage at 6.5%, you'll pay over $382,000 in interest alone — more than the original loan amount. Our calculator generates a complete schedule so you can see exactly where every dollar goes.
How to Use the Loan Amortization Calculator
- Enter the Loan Amount — the total amount borrowed (principal).
- Enter the Annual Interest Rate — the yearly rate on your loan (APR).
- Enter the Loan Term in years (e.g., 30 for a 30-year mortgage, 5 for an auto loan).
- Set the Start Month and Year for accurate payoff date display.
- View the summary cards: monthly payment, total amount paid, total interest, and interest as a percentage of your loan.
- Review the Annual Summary table and First 12 Months detail, then click Show Full Monthly Schedule for the complete amortization table.
Why Use Our Amortization Calculator?
- Full Amortization Schedule — Every single month, showing principal, interest, and remaining balance.
- Annual Summary View — See the big picture year by year before diving into monthly detail.
- Payoff Date — Toggle the full schedule to see your exact payoff month and year.
- 100% Free & Private — No account required, calculations run entirely in your browser.
- Any Loan Type — Works for mortgages, auto loans, student loans, personal loans, and more.
Frequently Asked Questions
Amortization is the structured repayment of a loan through fixed periodic payments. Each payment is split: the interest portion equals your remaining balance multiplied by the monthly interest rate (annual rate ÷ 12), and the principal portion is the rest of the payment. Because the balance decreases each month, the interest portion of each payment also decreases while the principal portion increases — even though your monthly payment stays the same. By the final payment, nearly the entire amount goes to principal because almost no interest remains.
The standard loan payment formula is: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of payments (years × 12). For a $300,000 loan at 6.5% for 30 years: r = 0.065/12 ≈ 0.005417, n = 360, monthly payment ≈ $1,896. This fixed payment covers interest first, then principal, throughout the life of the loan.
Principal is the portion of your payment that reduces the outstanding loan balance. Interest is the cost of borrowing — the lender's fee for providing the loan. In early payments, most of your money goes to interest: on a 30-year $300,000 mortgage at 6.5%, your first payment of ~$1,896 includes ~$1,625 in interest and only ~$271 toward principal. By year 20, the split reverses. This "front-loading" of interest is why paying just $100 extra per month can save tens of thousands of dollars and years off your loan.
Yes — any extra money paid above your regular monthly payment goes entirely toward reducing the principal, which reduces future interest charges and shortens your loan term. On a 30-year $300,000 mortgage at 6.5%, paying just $200 extra per month reduces the loan to about 23 years and saves approximately $80,000 in interest. Before making extra payments, check your loan for prepayment penalties (rare for modern mortgages but common on some personal and auto loans). When making extra payments, tell your lender to apply them to principal, not advance future payments.