What is a interest rate?
When you know the amount borrowed, regular payment and repayment count, this calculator estimates the rate that makes those cash flows balance. It assumes equal end-of-month payments, no extra fees and a fully amortizing fixed-rate loan. The result is an estimate, not a lender APR disclosure.
Formula and calculation method
The monthly rate is solved numerically from payment = P × r ÷ (1 − (1 + r)^−n). Nominal annual rate is the monthly rate multiplied by 12.
The result is only as reliable as the inputs and assumptions. This tool is educational and does not replace professional financial, medical, legal or academic advice.
How to use this calculator
- Enter the values requested in the calculator.
- Review the result panel; it updates when an input changes.
- Change one assumption at a time to compare scenarios.
- Check the formula and limitations before acting on the estimate.
Frequently asked questions
Is this interest rate calculator free?
Yes. You can use this calculator in your browser without creating an account.
How accurate is the result?
It applies the displayed formula to the values you provide. Real-world outcomes can differ because of fees, changing rates, individual circumstances or rules not represented in this estimate.
Are my inputs stored?
No. The calculation runs locally in your browser and the values are not submitted to FastSEOHub.