APR Calculator

What This Calculator Really Does

The interest rate tells you the cost of borrowing the principal. The APR tells you the cost of borrowing the money you actually receive — after fees, points and certain lender charges are folded in. Because APR expresses both in one annualized percentage, it is the only fair way to compare two offers whose fee structures differ.

This calculator solves for the rate that equates your loan proceeds (amount minus fees) with the stream of payments — the same method consumer-protection rules require lenders to disclose.

Everything runs locally in your browser; nothing you enter is transmitted or stored.

The Math, Explained Plainly

APR is the interest rate i that solves this equation:

Proceeds = Σ Paymentₜ / (1+i)ᵗ

• Proceeds — the amount you actually receive: principal minus fees and points.
• Paymentₜ — each scheduled payment (computed from the nominal rate for the given term).
• i — found numerically: the calculator iterates until the present value of payments equals the proceeds.

The result is annualized the same way lenders do it, so it is comparable with the APR printed on official disclosures.

How to Use It — In Order

1. Enter the loan amount — the gross principal.
2. Enter the nominal rate and term — these set the payment stream.
3. Enter the fees — origination, points, and lender charges that reduce your proceeds.
4. Read the APR — the single annual rate consistent with payments on the money you actually got.
5. Compare offers — the lower APR is the cheaper loan on identical terms, even if its rate looks higher.
6. Re-run with each offer's fees — never reuse one offer's fees for another's quote.

Worked Example, Verified by Hand

Offer A: $20,000, 4-year term, 5% nominal rate, no fees → payment = 20,000 × (0.05/12) × (1.0041667)⁴⁸ / ((1.0041667)⁴⁸ − 1) ≈ $460.41/month; APR equals the nominal 5.00% because proceeds equal principal.

Offer B: same loan but a $500 origination fee → you receive $19,500 yet still repay $460.41 × 48. The calculator solves the rate on those thinner proceeds and reports an APR meaningfully above 5% — that gap is the fee's true annual price.

Common Mistakes to Avoid

• Comparing APRs across different terms — a 15-year and 30-year APR are not directly comparable.
• Feeding in third-party costs the APR definition excludes (for mortgages: title, appraisal) — include only lender finance charges.
• Assuming the lowest nominal rate wins — fees can make a 4.75% loan cost more than 5.00%.
• Forgetting prepaid points, which raise APR above rate the most.
• Comparing APR with a monthly payment — they answer different questions.

Limitations

• Adjustable-rate and balloon structures need different APR treatment.
• What counts as a finance charge varies by product and jurisdiction — the calculator uses what you enter.
• APR assumes the loan runs to full term; early payoff changes the effective cost.

Expected Accuracy

The APR is solved numerically to high precision using the standard proceeds-equals-present-value method. With accurate fee inputs, results are consistent with lender disclosures computed under the same convention.

Privacy — Your Data Never Leaves This Device

The APR is computed in your browser by local iteration; there is no upload, no account, and no tracking of your inputs.

Related Tools & Guides

Natural next steps from APR:

• All Finance Calculators
• Amortization Calculator
• Loan EMI Calculator
• Loan Comparison
• Simple Interest Calculator

Sources & Standards

The APR method follows the standardized disclosure convention for consumer credit cost.

• CFPB — what APR includes and how it must be disclosed
• U.S. Federal Reserve — consumer credit regulations
• OCC — lending disclosure supervision

Bottom Line

Never shop loans on the interest rate alone. APR is the apples-to-apples number — it charges fees against the money you actually receive and expresses the result as one annual rate. Run every offer through it before you sign.

Frequently Asked Questions