Estimate the interest rate implied by a loan offer. Enter the amount borrowed, repayment term, and regular monthly payment to estimate the nominal annual rate and total interest.
Reverse loan-rate estimate • Monthly amortization • Annual or monthly scheduleLoan cost breakdown
Remaining loan balance
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Amortization schedule
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How to use the interest rate calculator
Enter the principal borrowed, the loan term in years and any additional months, and the regular monthly payment. The calculator estimates the fixed monthly rate that amortizes the loan over that term, then reports a nominal annual rate, an effective annual rate, total interest, and a payment schedule.
How the implied rate is found
The calculation solves for the monthly rate that makes the present value of all scheduled payments equal the loan amount. Each payment covers that month’s interest first; the remainder reduces principal. Interest is charged on the declining balance in this model.
View the payment formula
For principal P, monthly payment A, monthly rate r, and n payments: A = P × r ÷ [1 − (1 + r)−n]. The calculator numerically solves this equation for r. The nominal annual rate is 12 × r. The effective annual rate is (1 + r)12 − 1.
Questions and limitations
Why can a lender’s rate differ from this estimate?
Fees, payment dates, daily interest, lender rounding, variable rates, insurance, and balloon payments can change the actual cost. This estimate assumes no fees and equal end-of-month payments.
Is the estimated rate the APR?
No. The result is an implied rate based only on the loan amount, term, and regular payment entered. APR rules may include specific fees and use jurisdiction-specific methods. Do not treat this estimate as an official APR quote.
What if the payment is too low?
If the payment does not exceed the amount needed to repay principal at zero interest, a nonnegative amortizing interest rate cannot be determined for that term. Increase the payment or review the loan inputs.
Does the currency choice convert the loan?
No. It changes display formatting only. Enter all amounts in the same currency.
This estimate is for comparison and general information. Confirm the loan’s rate, fees, and payment terms with the lender.