Loan Amortization Calculator
Build a loan amortization schedule: monthly payment, interest vs principal each month, payoff date, and how much an extra monthly payment saves.
An amortization schedule shows how each fixed monthly payment on a loan is split between interest and principal, and how the balance falls to zero. Early payments are mostly interest; later ones are mostly principal. Use this calculator for car loans, personal loans, student loans or a mortgage, and add an extra monthly payment to see how much sooner you would be debt-free and how much interest you would save.
How to use this tool
- Enter the amount you borrowed and the yearly interest rate.
- Enter the loan term and choose years or months.
- Optionally add an extra amount you plan to pay toward principal each month.
- Set the first payment date, choose a monthly or yearly schedule, and read the results.
Formula
M = P × r / (1 − (1 + r)^−n)
M is the monthly payment, P the loan amount, r the monthly rate (yearly rate ÷ 12 ÷ 100) and n the number of payments. Each month, interest = balance × r, principal = M − interest (plus any extra payment), and the new balance is the old balance minus that principal. At 0% interest, M = P ÷ n.
Example
A $25,000 loan at 7.5% for 5 years has r = 0.075 ÷ 12 = 0.00625 and n = 60, so the payment is $500.95 a month. In the first month $156.25 is interest and $344.70 reduces the balance. Over the loan you pay $5,056.92 in interest. Adding $100 a month clears it after 49 payments instead of 60 and saves $1,013.61 in interest.
Frequently asked questions
Why does so little go to principal at first?
Interest is charged on the balance you still owe, which is highest at the start. As the balance shrinks, the interest part of each payment falls and the principal part grows, even though the payment stays the same.
Is it worth making extra payments?
Extra payments go straight to principal, so every later month charges interest on a smaller balance. Check that your loan has no prepayment penalty, and compare the interest saved with what the money could earn elsewhere.
Why is my lender's figure a few cents different?
Lenders round each payment to the cent and some calculate interest daily rather than monthly. The difference over a full loan is usually very small.
This tool gives an estimate for general information only. It is not financial, tax, legal or medical advice — check with a qualified professional before you rely on the result.
Last updated: 2026-10-30