Loan amortisation schedule calculator
See every repayment on a loan split into interest and principal, with the effect of extra repayments.
Assumes a fixed interest rate, monthly repayments and interest charged on the monthly balance. Lenders often calculate interest daily and may charge fees, so real figures differ slightly. Not financial advice.
How this calculator works
Each month the interest is the balance times the monthly rate (annual rate ÷ 12). The repayment is fixed at m = P × r ÷ (1 − (1 + r)−n), so whatever is left after interest reduces the balance. Early on most of each repayment is interest. Later most of it is principal.
Worked example: a $500,000 loan at 6.2% over 30 years has a repayment of $3,062.34 a month and costs $602,444 in interest. In the first year about $30,834 of the $36,748 you repay is interest and only $5,914 reduces the loan. Adding $500 a month cuts the loan to 20 years 11 months and saves about $209,582 of interest.
Sources and checks
You can cross-check results with:
Results can differ slightly from other tools because of rounding, fees and the assumptions each one makes.
Standard fixed-rate amortisation formula. Lenders add fees and may calculate interest daily.
Figures last checked: 29 October 2026. Spotted a mistake? Tell us.