Interest Rate Calculator
Solve for the interest rate from loan or savings terms.
Solves for the rate using bisection on the standard amortization formula. Real loans may include fees and points that change the true cost — see the APR calculator for that.
Recommended next steps
Related tools
Estimate monthly payments and total cost of a loan.
Estimate annual percentage rate including fees and points.
Estimate periodic payments needed to pay off a debt.
Frequently asked questions
It uses bisection on the standard amortization formula. The calculator narrows in on the monthly rate that makes the payment formula match the monthly payment you entered, then multiplies by 12 for the annual rate.
If the total of all your monthly payments doesn't cover the principal, no positive interest rate can make the math work. The calculator stops and shows "No solution" instead of guessing.
It returns the nominal annual rate implied by the principal, payment, and term — fees and points are not modeled. Use the APR calculator if you want to include up-front fees.
Last updated 2026-06-03.