APR Calculator

The interest rate a lender quotes tells you what percentage accrues on the balance you still owe — nothing more. It says nothing about origination fees, discount points, or other charges collected up front, which is exactly the gap APR exists to close. Annual percentage rate takes the same loan and asks a more complete question: given everything the borrower actually pays — the interest and the fees — what single annualised rate would explain the total cost, if all of it were treated as interest on the amount genuinely put in the borrower's hands?

That reframing matters most when comparing two competing offers. A loan advertised at a lower rate but loaded with fees can easily cost more overall than one at a slightly higher rate with no fees — and comparing note rates alone hides that entirely. APR is the number regulators require lenders to disclose specifically so a borrower does not have to do this arithmetic by hand.

The mechanics behind the calculation are easy to misread at first. Fees do not appear anywhere in the monthly payment — that figure is set purely by the note rate applied to the full loan amount, exactly as the lender advertises it. What the fees change is how much money the borrower actually receives to spend: paying $500 in fees on a $20,000 loan means only $19,500 is genuinely financed, even though $20,000 is being repaid with interest.

APR is the rate that makes sense of that mismatch — the annualised return a lender would need to earn if the same fixed payment stream were instead measured against the smaller amount actually disbursed. Because the same payment is now amortising less principal, the rate that explains it has to be higher than the note rate whenever any fee is present at all.

Regulators draw a specific line around which charges count toward APR, and getting this wrong is the most common source of a hand-calculated APR disagreeing with a lender's official disclosure.

A fixed dollar fee has a shrinking effect on the annualised rate the longer it is amortised over. Spread a $500 fee across five years of payments and it moves the APR noticeably above the note rate; spread that same $500 fee across thirty years and the effect nearly disappears, because the fee is a smaller share of a much larger total repaid. This is exactly why a short-term loan with fees can carry a surprisingly large APR-to-note-rate gap, and why APR is especially worth checking closely on shorter loans and adjustable-rate products where fees are amortised over a shortened initial period rather than the full term.

APR is a real improvement over the note rate alone, but it is not a complete picture of what a loan costs. It assumes the loan runs its full stated term, which understates the true cost of fees on a loan paid off or refinanced early — the fee gets amortised over fewer actual payments than APR assumed, so the realised cost is higher than the disclosed figure. It also cannot be used to compare a fixed-rate loan against an adjustable-rate one on equal footing, since an ARM's APR is calculated using its initial rate only and says nothing about what happens once that rate resets.