How loan payments work
Most consumer loans are fully amortizing: you pay the same amount every month, and each payment covers that month's interest first, with the rest reducing the balance. Because interest is charged on the remaining balance, early payments are mostly interest and later payments are mostly principal.
Three numbers decide the payment: how much you borrow, the interest rate, and how long you take to repay. A longer term lowers the monthly payment but increases the total interest — often by a lot.
APR versus interest rate
Lenders must show an APR (annual percentage rate), which folds certain fees into the rate so offers can be compared. If your loan has an origination fee that's deducted from the money you receive, the APR will be higher than the note rate. For comparing offers, use the APR; for the exact payment, use the note rate from your loan documents.
Ways to pay less interest
Choose the shortest term whose payment you can comfortably afford, pay extra toward principal when you can (use the amortization calculator to see the effect), and check whether your loan has prepayment penalties before paying it off early.
The loan payment formula
M = P × r ÷ (1 − (1 + r)^−n)- M = monthly payment
- P = amount borrowed
- r = monthly interest rate (APR ÷ 12)
- n = number of monthly payments
Example
- Borrow $25,000 at 7.5% APR for 5 years.
- r = 0.075 ÷ 12 = 0.00625; n = 5 × 12 = 60.
- M = 25,000 × 0.00625 ÷ (1 − 1.00625^−60) = $500.95 per month.
- 60 payments × $500.95 = $30,057, so the loan costs about $5,057 in interest.
Frequently asked questions
Does this work for car loans and personal loans?
Yes — any fixed-rate loan with equal monthly payments. For loans with variable rates, balloon payments or interest-only periods, the real payments will differ.
Why is my lender's payment slightly different?
Lenders may round the rate, count days differently, or include fees or insurance in the payment. Differences of a few cents to a few dollars are normal.
Is a shorter loan term always better?
It always costs less interest, but a payment you can't keep up with costs more in the end. Many people take a longer term for flexibility and pay extra when they can, as long as there's no prepayment penalty.
What about a 0% loan?
With a 0% rate the payment is simply the amount divided by the number of months, and there is no interest. Check for deferred-interest terms, which charge all the interest back if you don't pay in full by the deadline.
Sources
Last reviewed for 2026. How we calculate.