APR vs. Interest Rate: The Math, Shown Step by Step

Two numbers that answer different questions

With no fees, the two are the same. A $10,000 loan at 9% for 36 months with no fee has a 9.00% APR. The moment a fee appears, the APR climbs above the rate, and the bigger the fee or the shorter the loan, the wider the gap. The CFPB's advice is simple: compare APR to APR, never one lender's APR to another's interest rate.

Turning a fee into an APR

Take the same $10,000 loan at 9% for 36 months, now with a 4% origination fee deducted from the money you receive.

1. 1 Find the payment. Interest is charged on the full $10,000, so the payment is $10,000 × r ÷ (1 − (1 + r)^−36), where r = 9% ÷ 12 = 0.75% a month. That gives $318.00.
2. 2 Find what you actually get. The $400 fee comes off the top, so $9,600 lands in your account. That's the amount financed on your disclosure.
3. 3 Find the rate that links the two. Ask: at what monthly rate are 36 payments of $318.00 worth exactly $9,600 today? Solving gives about 0.9844% a month.
4. 4 Annualize it. 0.9844% × 12 = 11.81% APR.
5. 5 Check the box. Total of payments: 36 × $318.00 = $11,448.00. Finance charge: $11,448.00 − $9,600.00 = $1,848.00, which is the $1,448.00 of interest plus the $400 fee.

You don't have to do this by hand. The APR calculator solves step 3 for any amount, fee and term, and Regulation Z requires the lender's own figure to be accurate within 1/8 of a percentage point on a regular loan.

Same fee, different term, different APR

A fixed fee is spread over however many months you pay. Spread it thin and the APR barely moves; squeeze it into one year and it jumps.

Notice the trap in the last row: the 60-month loan has the lowest APR and the highest total of payments. APR measures cost per year, not cost overall. When terms differ, look at the total too; our guide to comparing loan offers works through three quotes this way.

When the APR understates what you pay

• Paying off early. The APR assumes you keep the loan to the end. Pay off the 36-month loan above after 12 payments, by covering the $6,960.69 balance, and the $400 fee has been spread over one year instead of three: your actual cost works out to about 13.97% a year, not 11.81%. If you expect to repay early, a no-fee loan often wins.
• Costs outside the finance charge. Late fees and other default charges aren't in the APR. Optional credit insurance is left out too, as long as it's truly voluntary, its cost is disclosed and you sign a separate request for it.
• Variable rates. On a variable-rate loan, the APR is calculated as if today's rate never changes. The disclosure must explain how and when the rate can rise and give an example.
• Dollars, not percentages. APR doesn't tell you the total. The finance charge and total of payments do.

Fees are where most of these surprises start; our guide to origination fees shows how to gross up a loan so you still receive the amount you need.

Where you'll see each number

Before you sign an installment loan, Truth in Lending requires a disclosure box with four figures: the annual percentage rate, the finance charge, the amount financed and the total of payments. The APR and finance charge must be more conspicuous than any other disclosure except the lender's name. The interest rate usually appears in the promissory note and on the lender's offer screen, not in the box.

For reference, the Federal Reserve reported that commercial banks averaged 11.90% on 24-month personal loans in August 2026. On a personal loan, a quote well below that with a large fee may not be the bargain it looks like until you see the APR. Ranges by credit score are on the personal loans page.

For servicemembers, the MAPR goes further

The Military Lending Act uses its own measure, the Military Annual Percentage Rate, and caps it at 36% for active-duty servicemembers, including those on active Guard or Reserve duty, and their covered dependents. The MAPR counts more than the APR does:

• Finance charges, including the interest and origination fees in the regular APR.
• Credit insurance premiums and debt cancellation or suspension fees.
• Fees for add-on products sold with the credit.
• Certain application and participation fees.

The cap covers most consumer credit, including payday, vehicle title and installment loans and credit cards. Mortgages, home equity loans and loans secured by the car or other property being bought are not covered. MLA loans also can't carry a prepayment penalty or require mandatory arbitration.

Common questions