What Is APR and How to Calculate It on a Loan

Interest rate vs. APR

The interest rate is what the lender charges on the principal. The APR (Annual Percentage Rate) rolls in most fees — origination, points, processing — so you can compare loans with different cost structures on equal footing.

A loan with a lower interest rate but high fees can have a higher APR than a loan with a slightly higher rate and no fees.

The basic intuition

If you borrow $10,000 and pay$200 in fees, you only receive $9,800. Your monthly payments are still based on$10,000, but the true amount you can use is smaller. APR captures that reality.

How to estimate APR

For a fixed installment loan, APR is the rate that makes the present value of your payments equal to the amount you actually receive after fees.

In plain terms: solve for the interest rate where the loan's cash flows net to zero.

[ 0 = \text{net proceeds} - \sum_{t=1}^{n} \frac{\text{payment}}{(1 + \text{APR}/12)^t} ]

This usually requires numerical methods (trial and error or a solver). Our APR calculator does this for you.

Worked example

• Loan amount: $10,000
• Origination fee: $200 (deducted upfront)
• Interest rate: 8%
• Term: 3 years

You receive $9,800, but your payments are based on$10,000. The monthly payment at 8% is about $313.36. The APR is the rate that makes$9,800 equal to 36 payments of $313.36. It works out to roughly 8.72%.

Why APR matters

• It lets you compare loans with different fee structures.
• It reflects the true cost of borrowing.
• It is required by law in many lending disclosures.

What APR does not include

APR typically does not include late fees, optional products like credit insurance, or costs that depend on your behavior after origination. Read the full disclosure.

Try it

Use the APR calculator to find the true cost of any loan offer, or compare two loans side by side with the loan comparison calculator.