P = principal, r = monthly rate (annual rate ÷ 12), n = number of payments (years × 12). Because interest is charged on the outstanding balance, it's heaviest at the start — so even small extra payments early on cut the total interest and shorten the loan significantly.
How the loan calculator works
This calculator uses the standard fixed-rate amortization formula to work out your monthly payment on a loan such as a personal loan, auto loan, or mortgage (principal and interest only). Drag any slider and every figure — payment, interest, payoff — updates instantly.
The monthly payment is M = P·r·(1+r)ⁿ / ((1+r)ⁿ − 1), where P is the
loan amount, r is the monthly interest rate, and n is the number
of monthly payments.
The power of extra payments
Use the extra-payment slider to see how paying a little more each month shortens your loan and slashes total interest. Because interest is charged on the remaining balance, every extra dollar of principal compounds into real savings over the life of the loan.
Estimates principal and interest only; for information, not financial advice.