Interest Rate Calculator

Enter principal, monthly payment, and term to solve for the approximate nominal annual interest rate and APR-style monthly rate.

Principal / amount financed

Monthly payment

Term

Term unit

—Nominal annual rate

—Monthly rate

—Effective annual rate

—Total interest

—Solves the fixed-payment amortization equation numerically.

This calculation estimates the rate implied by principal, payment, and term. Fees or irregular cash flows can make a lender-disclosed APR differ.

How to use this Interest Rate Calculator

Estimate the annual interest rate implied by a fixed loan payment. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.