Loan calculator.
Monthly payment, total interest and total cost for any fixed-rate loan.
How loan payments work
A fixed-rate loan is repaid in equal monthly instalments using the same amortisation formula as a mortgage: each payment covers the month's interest first, with the rest reducing the balance. Early on, most of the payment is interest; as the balance falls, more goes to principal. Two levers matter most. A higher rate raises both the monthly payment and the total interest. A longer term lowers the monthly payment but increases the total interest paid, sometimes dramatically — stretching a car loan from four years to seven cuts the payment but can add thousands in interest. This works for car, personal and student loans; for a home loan with taxes and insurance, use the mortgage calculator.
A worked example
Borrow $25,000 at 7.5% APR over 5 years. The monthly rate is 7.5% ÷ 12 = 0.625%, spread across 60 payments, which gives a payment of about $501. Over the full term you repay roughly $30,045, so the interest is about $5,045 on top of the $25,000 you borrowed.
Watch how the split shifts. In month one, interest is $25,000 × 0.625% = $156, leaving $345 to cut the balance. By the final payment almost the whole $501 is principal. Keep the same loan but stretch it to 7 years and the payment drops to about $385 — yet total interest climbs past $7,300, because the balance sits unpaid for longer.