Loan Payment Calculator
Find the monthly payment, total interest and payoff time for a fixed-rate loan. Add an extra monthly payment to see how much interest and time you can save.
Last updated: October 2026How it works
Loan payment formula
Payment = P × r × (1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is the amount borrowed, r is the monthly rate (annual rate ÷ 12 ÷ 100) and n is the number of monthly payments. Total interest is payment × n − P.
Worked example
A $30,000 loan at 7.5% for 5 years has a monthly payment of about $601 and costs roughly $6,068 in interest. Adding $100 a month pays it off in 4 yr 2 mo and saves about $1,050 in interest.
Frequently asked questions
How is a monthly loan payment calculated?
The calculator uses the standard amortization formula: payment = 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 months.
Can I use this as an auto loan calculator?
Yes. It works for any fixed-rate installment loan, including auto, personal, student and boat or RV loans. Enter the amount you are financing after any down payment.
What is the difference between interest rate and APR?
APR includes certain lender fees on top of the interest rate, so it is usually a little higher. Entering the APR gives a close estimate, and your lender's loan estimate shows the exact figures.
Do extra payments really save interest?
Yes. Extra money goes straight to principal, which lowers the balance that interest is charged on, so you pay the loan off sooner and pay less interest overall. Check that your loan has no prepayment penalty.
Does this include taxes, fees or insurance?
No. It covers principal and interest only. Sales tax, title and registration fees, and insurance are separate costs.