About the Loan calculator
Use this loan calculator for personal loans, student loans, business loans or anything else with a fixed rate and equal monthly payments. Enter the amount, APR and term, and you get the monthly payment, the number of payments, total interest and total paid.
It also shows interest as a percentage of the amount borrowed, a principal-versus-interest chart and a payment-by-payment schedule. The term can be set in years plus extra months, so a 42-month loan is easy to enter. The working section walks through the formula with your numbers.
How to use it
- Enter the Loan amount you plan to borrow.
- Enter the Interest rate (APR) from your loan offer.
- Set the Term (years), and use + months for terms like 3 years 6 months.
- Read the monthly payment, total interest and interest as a % of the loan.
- Scroll the payment schedule to see each payment’s interest, principal and balance.
The formula
The payment for a fully amortizing fixed-rate loan is:
M = P × r(1 + r)^n ÷ ((1 + r)^n − 1)
- M — monthly payment
- P — loan amount
- r — monthly rate = APR ÷ 12 ÷ 100
- n — total months = years × 12 + extra months
Total interest is everything you pay minus what you borrowed:
Total interest = M × n − P
If the rate is 0%, the payment is simply P ÷ n.
How term length changes the cost of a loan
A longer term lowers the monthly payment but raises the total interest, because the balance stays outstanding for longer. A $20,000 loan at 7.5% over 5 years costs about $400.76 a month and roughly $4,046 in interest, about 20% of the amount borrowed.
Stretch the same loan to 7 years and the payment falls, but you pay interest for 24 more months. Shorten it to 3 years and the payment rises while the interest drops sharply. The “Interest as % of loan” line makes this easy to compare: try a few terms and pick the shortest one whose payment fits your budget comfortably.
Also compare offers by APR rather than the payment alone. Two loans with the same payment can have very different total costs if their terms differ.
APR versus interest rate
The interest rate is the cost of borrowing the principal. The APR (annual percentage rate) also folds in certain lender fees, spread across the term, so it is the better number for comparing offers. If an origination fee is taken out of the loan proceeds, the APR will be higher than the note rate.
This calculator applies whatever rate you enter as a monthly rate of APR ÷ 12. If you enter the note rate, the payment matches your lender’s figure closely. If you enter the APR, the result gives a slightly higher payment that reflects the fees. Already have a payment and want the rate? The interest rate calculator solves it backward.
Frequently asked questions
How do I calculate a monthly loan payment?
Divide the APR by 12 to get the monthly rate r, count the months n, and use M = P × r(1 + r)^n ÷ ((1 + r)^n − 1). The calculator does this and shows each step.
Does this work for interest-only or variable-rate loans?
No. It assumes a fixed rate and equal payments that fully pay off the loan by the end of the term.
How much interest will I pay in total?
Multiply the payment by the number of payments and subtract the amount borrowed. The result appears as Total interest.
Can I enter a term that isn’t a whole number of years?
Yes. Use the + months box for 1 to 11 extra months, or enter 0 years and up to 11 months for a very short loan.
Last updated October 24, 2026. Results are estimates for education and planning — see our disclaimer.