Loan implied rate calculator

Fixed-rate, level-payment model: solves for the nominal annual rate with monthly compounding such that the payment amortizes the principal over the term. Related pages on this site: Loan calculator, Mortgage calculator; combined note rate and upfront fees are modeled on the APR calculator.

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

Result
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How this calculation works

What each input means

Loan principal — Amount being amortized.
Monthly payment — Level payment assumed each month.
Loan term (years) — Converted to months (rounded) for payment count.

Formula used

Solves monthly rate r such that principal equals the present value of n payments at r, then quotes nominal annual rate ≈ 12 × r (monthly compounding) plus an effective annual rate.

Assumes standard fixed-rate amortization; not for interest-only, balloon, or negative amortization schedules.

How this result is estimated

This loan rate calculator applies the formulas described on this page to the values you enter. Outputs are not financial, tax, legal, or medical advice.

Inputs are user-provided and may include rounding.
Where accuracy, eligibility, or obligations matter, rely on official disclosures and licensed professionals.

Last reviewed: 2026-04-17

Frequently asked questions

What rate is this solving for?

A nominal annual rate with monthly compounding that makes your fixed monthly payment amortize the principal over the term—the usual level-payment mortgage-style assumption.

Why might the calculator say my payment is too low?

If the payment cannot amortize the principal over that many months at any nonnegative interest rate, no solution exists for this model.

Does this include upfront fees?

No. Net-proceeds fee treatment alongside full-principal amortization appears on the APR calculator page on this site.

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