Interest Rate Calculator

Use this free interest rate calculator to estimate an annual rate from loan amount, fixed monthly payment, and repayment term.

All tools

Formula steps Estimate limits shown Examples included Private history

Principal ($)Monthly payment ($)Loan term (years)

Estimated annual rate5.9999967108%

$25,000, $483.32/mo for 5 years

Monthly rate: 0.4999997259%
Total interest: $3,999.20
Total paid: $28,999.20

This estimated rate is not APR and does not include fees.

Formula steps

Start with the fixed payment, principal, and number of monthly payments.
Search for the monthly rate that makes the loan formula match the payment.
Convert the monthly rate to an estimated nominal annual rate.
Total interest equals monthly payment times months minus principal.

How to use the interest rate calculator

Enter the requested dollar amounts, rates, terms, tax settings, or contribution details.
Use rates as percentages, such as 6.5 for 6.5%, and check whether a field asks for a monthly or annual amount.
Press the calculate button to see the answer, supporting metrics, and formula steps.
Use the result as a planning estimate only, then copy it if the assumptions look right.

Common uses

Estimate the rate implied by a loan payment offer.

Compare payment quotes when the rate is missing.

Check whether a payment is possible for a principal and term.

Use the answer alongside loan and payment calculators.

Examples

Payment quote $25,000 principal, $483.32/month, 5 years

Estimated annual rate

Higher payment $15,000, $350/month, 4 years

Implied rate estimate

Impossible payment Payment below zero-interest payoff

Calculator shows an input warning

Frequently asked questions

Quick answers about formulas, rates, payment assumptions, estimate limits, examples, and private in-browser history.

What can I use the Interest Rate Calculator for?

Use it for quick planning, comparison, and what-if estimates before you check exact numbers with a lender, tax professional, payroll provider, or financial adviser.

How does the Interest Rate Calculator calculate the result?

The calculator searches for the monthly rate that makes the fixed-payment loan formula match your monthly payment, then converts that to an annual rate.

Is this financial, tax, or legal advice?

This is an estimated nominal annual rate. It does not calculate APR with fees, compounding disclosures, promotional terms, variable rates, or lender-specific rules.

Are my finance inputs private?

Yes. The calculator runs in your browser tab. Recent answers stay only on the page while you use it and are not sent to a server.