APR Calculator — Find the True Cost of Any Loan

An APR calculator reveals the true cost of borrowing that the advertised interest rate alone hides. Lenders quote a nominal interest rate, but origination fees, points, and closing costs add real cost on top of it — APR (Annual Percentage Rate) folds all of that into a single number so two loan offers can be compared honestly. A loan with a lower interest rate but higher fees can easily have a higher APR than a loan with a slightly higher rate and no fees. This calculator solves for the exact APR given your loan amount, fees, nominal rate, and term, using the same method lenders are legally required to disclose under Truth in Lending Act regulations.

How to use this APR Calculator

1. 1Enter the loan amount — the total principal before fees are deducted.
2. 2Enter total fees and closing costs: origination fees, points, underwriting fees, or any other cost charged to originate the loan.
3. 3Enter the nominal interest rate — the advertised rate from the loan offer, not the APR.
4. 4Enter the loan term in years.
5. 5The calculator computes your monthly payment from the nominal rate, then solves for the true APR — the rate that would produce that same payment if the fees were spread across the loan instead of charged upfront.

APR formula explained

Unlike a simple interest rate calculation, APR cannot be solved with a single direct formula — it requires working backward from the actual monthly payment. The calculator first computes the standard monthly payment using the nominal rate on the full loan amount. It then finds the interest rate that would produce that exact same monthly payment if it were applied only to the amount you actually received — the loan amount minus fees. That rate is the APR: a higher number than the nominal rate, because the same payment is now being attributed to a smaller effective loan amount.

Calculate true APR: $20,000 loan, $500 fees, 6.5% nominal rate, 30-year term

1. 01Loan amount: $20,000. Nominal rate: 6.5% → monthly rate = 0.065 ÷ 12.
2. 02Term: 30 years → n = 30 × 12 = 360 payments.
3. 03Monthly payment on $20,000 at 6.5%: $126.41.
4. 04Solve for the rate that produces a $126.41 payment on $20,000 − $500 = $19,500.
5. 05That rate is 6.745% — the true APR.

What affects the gap between interest rate and APR?

Tips and things to know

• ✓Always compare APR, not the advertised interest rate, when shopping multiple loan offers — it is the only number that accounts for fees consistently across lenders.
• ✓A "no closing cost" loan usually has a higher nominal rate baked in instead — its APR will often be very close to its interest rate, which is itself useful information when comparing against a low-rate, high-fee alternative.
• ✓For loans you plan to pay off or refinance early, a lower-fee, higher-rate option can have a lower effective cost than a low-rate, high-fee option, even if its APR looks higher over the full term — APR assumes you keep the loan to maturity.
• ✓Request the Loan Estimate (for mortgages) or equivalent fee disclosure in writing before comparing APRs — verbal rate quotes often omit fees that only appear in the official documentation.
• ✓A large gap between nominal rate and APR is a signal to ask the lender for an itemized breakdown of every fee — it is your right to know exactly what is being charged before closing.

APR Calculator — bottom line

APR is the number you should be comparing between loan offers, not the interest rate — but most borrowers get this wrong because the interest rate is the number lenders advertise most prominently. The interest rate tells you the cost of borrowing the principal expressed as a yearly percentage. The APR tells you the true cost of the loan including all required fees — origination fees, broker fees, mortgage points, closing costs — expressed as a single annual rate for apples-to-apples comparison. On a mortgage, the difference between the interest rate and APR is often 0.1–0.5% after rolling in closing costs. On a personal loan with a 5% origination fee, the APR can be meaningfully higher than the stated rate. The most common mistake is accepting a lender's "lower rate" offer without checking the APR. A mortgage at 6.75% with $8,000 in points and fees may have an APR of 7.1%, making it more expensive than a 7.0% loan with minimal fees, depending on how long you keep the loan. The break-even depends on your expected hold period: a loan with higher upfront costs but lower APR may make sense if you hold for 10+ years, but not if you expect to refinance or sell in 3–5 years. Practical action steps: (1) get the APR, not just the interest rate, from every lender before comparing; (2) use this calculator to back-calculate the APR from any loan offer where only the payment and fees are quoted; (3) for mortgages, run the APR at your expected hold period — if you sell after 7 years, amortize the closing costs over 84 months, not 360. The Amortization Schedule Calculator lets you see exactly how each monthly payment splits between interest and principal over the full loan term.

Official resources and further reading