Loan amortization calculator
Find the monthly payment and total interest for any fixed-rate loan.
Runs 100% in your browser- Monthly payment
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- Total interest
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- Total repaid
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- Payments
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How to calculate loan amortization
- Enter the loan. Type the loan amount and annual interest rate.
- Set the term. Enter the term in years (e.g. 30 for a mortgage, 5 for a car loan).
- Read the payment. See the monthly payment, total interest and total repaid.
What amortization means
An amortizing loan is one you repay in equal instalments that fully clear the debt by the end of the term — mortgages, car loans and most personal loans all work this way. The payment never changes, but what it's made of does. Each month, interest is charged on the balance you still owe, and the rest of your fixed payment chips away at the principal. This calculator solves the standard payment formula for you and reports the monthly payment, the total interest over the life of the loan, and the total you'll repay — the three numbers that actually tell you what a loan costs.
Where your payment goes — and why early payments barely dent the balance
Because interest is charged on the outstanding balance, and that balance is highest at the start, your early payments are mostly interest with only a sliver going to principal. As the balance slowly falls, the interest portion shrinks and the principal portion grows, so the loan pays down faster and faster toward the end — the mirror image of the snowball in the compound interest calculator, working against you instead of for you. It's also why making extra principal payments early saves disproportionate interest: every dollar off the balance now avoids interest for the loan's whole remaining life.
What lowers the true cost — and what this leaves out
Two levers cut total interest: a lower rate (less charged on every balance) and a shorter term (the money is borrowed for less time). A shorter term raises the monthly payment but can more than halve the lifetime interest, which is the trade-off worth modelling here before committing. Two honest limits: this shows principal and interest only, so a real mortgage bill may add escrow for taxes and insurance (PITI) and possibly PMI; and it assumes a fixed rate, so an adjustable-rate loan will diverge. To compare how rates are actually quoted, convert with the APY calculator.
Educational tool only — not financial advice. Principal and interest only; excludes taxes, insurance and fees.
Frequently asked questions
- Amortization is paying off a loan with equal periodic payments. Early payments are mostly interest; over time more of each payment goes to principal. This calculator gives the monthly payment, total interest and total paid.
- Payment = P · i ÷ (1 − (1 + i)^−n), where P is the loan amount, i the monthly rate (annual ÷ 12), and n the number of months. The calculator does this for you.
- Because interest is charged on the outstanding balance, which is largest at the start. Each payment is split: interest on the current balance first, and whatever is left reduces the principal. Early on the balance is high, so interest eats most of the payment; as the balance falls, the principal share of each fixed payment grows — that shifting split is the amortization schedule.
- Both cut the total interest, but differently. A lower rate reduces the interest charged on every balance. A shorter term raises the monthly payment but means you borrow the money for less time, so far less interest accrues overall — a 15-year loan can cost less than half the total interest of a 30-year one at the same rate, despite the higher monthly figure.
- Yes — any fixed-rate amortizing loan. Enter the amount, annual rate and term in years. The principal-and-interest math is identical; only the typical amounts and terms differ.
- No — it's principal and interest only. A real mortgage payment often also includes escrow for property taxes and insurance (together "PITI"), and possibly PMI, so your actual monthly bill can be higher than the figure here.
- No — it computes in your browser.