APR Calculator
Solve the monthly rate that equates amount financed with equal scheduled payments, then report nominal APR and effective annual rate alongside amount financed and total payments.
How to use this calculator
Enter loan amount, prepaid fees, equal monthly payment, and number of monthly payments.
Review cash-flow dates, prepaid finance charges, excluded fees, compounding convention, irregular payments, disclosure rules, and loan type.
Read amount financed, estimated nominal APR, effective annual rate, and total payments.
Formula
Find monthly rate i such that amount financed = Σ(payment ÷ (1+i)^t). Nominal APR = 12i; effective annual rate = (1+i)^12 − 1; total payments = payment × months.
Worked example
For a $20,000 loan with $500 prepaid fees and 36 monthly payments of $620, the modeled amount financed is $19,500 and estimated nominal APR is about 8.99%.
Assumptions and limits
- This is an estimate for the entered cash flows and does not determine which fees a lender must include under a specific disclosure law.
- APR Calculator treats the entered values as estimates and does not infer missing project, account, or personal details.
- Calculations retain working precision except where the cited method requires an intermediate rounding step; displayed values are then formatted separately. Source rules and dated rates must be rechecked when they change.
Sources
- Consumer Financial Protection Bureau: What is the difference between a mortgage interest rate and an APR?APR, interest-rate, and fee distinctions. Reviewed 2026-08-14.
- Consumer Financial Protection Bureau: Determination of annual percentage rate — Regulation Z § 1026.22Official formula or method source used by this calculator. Reviewed 2026-08-14.
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Verification
How this calculator is checked
Trust comes from reproducible evidence, not model confidence. You can inspect the formula, assumptions, worked example, and cited sources on this page.
- Versioned calculationFormula logic is kept separate from the interface and covered by automated registry and behavior checks.
- Cited evidenceSources linked for independent checking: 2.
- Transparent AI useAI may assist drafting or adversarial review. Agreement between models is not proof, and no human expert review is claimed unless a named reviewer is shown.
Frequently asked questions
How does the APR Calculator work?
Find monthly rate i such that amount financed = Σ(payment ÷ (1+i)^t). Nominal APR = 12i; effective annual rate = (1+i)^12 − 1; total payments = payment × months.
What information should I enter in the APR Calculator?
Enter loan amount, prepaid fees, equal monthly payment, and number of monthly payments, then verify cash-flow dates, prepaid finance charges, excluded fees, compounding convention, irregular payments, disclosure rules, and loan type.
What should I verify before using this APR Calculator result?
This is an estimate for the entered cash flows and does not determine which fees a lender must include under a specific disclosure law.
Last updated 2026-08-25 · level-payment-irr-v1 · content-2026-08-14 · Published by YunFanLabs