How to use the loan calculator
Pick what you want to find. Payment takes the loan amount, interest rate and term and gives you the regular payment. Loan amount works backward from a payment you can afford to the most you could borrow. Payoff time takes the amount and a payment and tells you how long the loan will last.
Choose monthly, biweekly or weekly payments, and add an optional extra amount to see how much sooner you would be debt-free and how much interest you would save. Nothing you type leaves your device; the maths runs in your browser.
This page works for any fixed-rate installment loan. For a loan with an origination fee and the APR that comes with it, use the personal loan calculator; for a car purchase with a down payment, trade-in and sales tax, use the auto loan calculator.
The loan payment formula
A fixed-rate loan is repaid in equal payments that cover that period's interest plus some principal. The payment is M = P × r ÷ (1 − (1 + r)−n), where P is the amount borrowed, r the rate per payment (the yearly rate ÷ 12 for monthly payments) and n the number of payments.
Worked example (the default above): $20,000 at 8% for 5 years is 60 monthly payments of $405.53. Over the loan you pay $24,331.67 in total, of which $4,331.67 is interest. US lenders must show you these same figures before you sign: the amount financed, the finance charge, the APR and the total of payments (CFPB: Regulation Z §1026.18, content of loan disclosures).
Where each payment goes
Interest is charged on the balance you still owe, so early payments are mostly interest and later ones mostly principal. In the example, the first payment of $405.53 is $133.33 interest and $272.19 principal. The last one is just $2.69 interest and $402.84 principal.
The yearly table shows the balance falling slowly at first and faster near the end. Extra principal paid early cuts the balance that every later payment is charged interest on, which is why it saves so much. To see every payment with its date, principal, interest and balance, and download it as a spreadsheet, use the amortization calculator.
How the term and the rate change the cost
A longer term lowers the payment but raises the total interest. $20,000 at 8%:
3 years: $626.73 a month, $2,562.18 interest
5 years: $405.53 a month, $4,331.67 interest
7 years: $311.72 a month, $6,184.84 interest
The rate matters just as much. Over 5 years the same loan costs $3,199.36 in interest at 6% and $5,496.45 at 10%. When you compare offers, look at the APR as well as the rate: the APR adds points, fees and other charges to the interest rate, so it is usually higher (CFPB: What is the difference between an interest rate and an APR?).
How much can I borrow?
Turn the question around. If you can afford $400 a month, at 8% over 5 years you could borrow about $19,727.37. Lenders also look at your debt-to-income ratio, which is all your monthly debt payments divided by your gross monthly income. The CFPB's example is $2,000 of payments on $6,000 of income, a ratio of 33% (CFPB: What is a debt-to-income ratio?). Limits differ by lender and loan type.
Before you set a payment, check what you take home with the paycheck calculator.
Paying a loan off faster
Paying $100 more each month on the example loan pays it off 1 year 1 month sooner and saves $1,036.37 in interest. Choosing Payoff time lets you test any payment: at $500 a month the loan is gone in 3 years 11 months.
Biweekly payments help too. Paying half the monthly amount ($202.76) every two weeks adds up to 26 half-payments, or 13 full payments a year, and repays the loan in 4 years 6 months instead of 5 years. Splitting the loan into biweekly payments over the same 5 years ($186.89 each) saves much less, because you still make the same yearly total.
Ask before you prepay. Some loans charge a prepayment penalty if you pay off all or a large part of the balance early, though small extra principal payments usually do not trigger it (CFPB: What is a prepayment penalty?).
Tips
Shop the APR and the total. Two loans with the same payment can cost very different amounts if one has a longer term or higher fees.
Variable rates change. This calculator assumes a fixed rate. If your rate can adjust, your payment and total cost can rise.
Know the interest method. Most consumer loans charge simple interest on the balance; the simple interest calculator shows how that works over days or months.
Weigh paying off debt against saving. Extra payments earn you the loan's rate, guaranteed. Compare that with what your savings would earn in the compound interest calculator.
Updated October 28, 2026 · Sources are linked in the text above · How we build and check our calculators