Interest Rate Calculator
Reverse-engineer the rate on a loan. Enter the amount borrowed, the term, and the fixed monthly payment, and we'll find the annual percentage rate that fits.
Loan details
How to use this calculator
1. Enter the loan amount
Type the principal — the sum you borrowed before any interest. This is the figure the lender advanced to you.
2. Set the term in years
Give the full length of the loan in years. The calculator converts it to a number of monthly payments behind the scenes.
3. Enter your monthly payment
This is the fixed amount you pay each month. With the amount, term, and payment all known, the rate is the only thing left to solve for.
4. Read the APR and totals
The headline number is the annual rate implied by your payment. The cards show the total you'll repay and how much of that is interest. To go the other way and find a payment from a known rate, use the Loan Calculator.
About interest rate solving
How does this calculator find the rate?
You already know the loan amount, the term, and the monthly payment, so the only unknown is the rate. The calculator searches for the monthly rate that makes the standard amortization payment match what you entered, then multiplies it by 12 to report the annual percentage rate.
Why does my result sometimes say invalid?
If the total of all your monthly payments is not more than the loan amount, there is no positive interest rate that fits — you would be paying back less than you borrowed. Raise the monthly payment or the term so the total exceeds the loan amount.
Is APR the same as APY?
Not quite. The APR here is the monthly rate times 12 (a nominal annual rate). The effective annual rate, or APY, also accounts for monthly compounding and is slightly higher. Lenders quote APR for loans, so that's what we report.