How to Calculate APR by Hand, Step by Step

APR (Annual Percentage Rate) exists to answer one question a bare interest rate can't: what does this loan really cost per year once fees are included? Here's the simplified formula lenders use for a basic fixed-term loan, worked through with real numbers.

The Simplified Formula

APR = ((Fees + Total Interest) ÷ Principal) ÷ Loan Term in Years × 100

Worked Example

1. 1

   Gather the loan's real numbers

   You borrow $10,000 for 3 years, pay $1,200 in total interest, plus a $300 origination fee.

2. 2

   Add the fees to the total interest

   $1,200 + $300 = $1,500 total cost of borrowing.

3. 3

   Divide by the principal

   $1,500 ÷ $10,000 = 0.15 (15% over the full loan term).

4. 4

   Divide by the number of years, then convert to a percentage

   0.15 ÷ 3 = 0.05 × 100 = 5% APR.

Why APR Is Usually Higher Than the Interest Rate

If this loan's stated interest rate alone was 4%, the 5% APR above reveals the real cost once that $300 fee is spread across the loan term -- APR is always equal to or higher than the plain interest rate for the same loan, never lower, because it can only add costs on top, not subtract them.

Try it instantly — freeAPR CalculatorOpen Calculator →

Frequently Asked Questions

Why do two loans with the same interest rate sometimes have different APRs?

Because APR bakes in fees the plain interest rate doesn't -- an origination fee, points, or mandatory insurance can make a lower-interest-rate loan actually cost more overall than a higher-rate loan with fewer fees. APR is designed specifically so loans can be compared fairly on total cost, not just the headline rate.

Is a lower APR always the better deal?

Usually, for loans of the same term and type -- but APR assumes you keep the loan for its full term. If you plan to pay off or refinance early, a loan with a higher APR but lower upfront fees can sometimes cost less in practice, since you never "recover" those fees over a full term that never happens.