APR vs interest rate
The interest rate sets your payment. The APR tells you what the loan costs once the lender’s fees are counted. Here is the difference, worked through with numbers.
The short version
The interest rate is what you pay for the money. The APR is what you pay for the loan.
Those are different because getting a loan costs more than the interest on it. The lender charges points, an origination fee, underwriting, sometimes mortgage insurance. All of that is money you hand over to borrow, and none of it shows up in the interest rate. The APR puts it back in and re-expresses the whole cost as a yearly rate.
If a lender charges you nothing but interest, the two numbers are identical. The gap between them is a direct measure of the lender’s fees.
What each number is used for
The interest rate determines your payment. It is applied to your balance every month, and the amortization schedule is built from it. The APR never touches your payment — a 6.5% loan with a 6.59% APR still bills you at 6.5%.
The APR is for comparing offers. That is its entire purpose under the Truth in Lending Act: one number that lets you hold two quotes side by side without reverse-engineering each fee sheet.
This trips people up constantly. Borrowers see the higher APR on their disclosure and assume they were quoted a bait-and-switch rate. They weren’t. The APR is not the rate they will be charged; it is the rate that would have produced the same total cost if there had been no fees.
A worked example
Take $300,000 over 30 years at 6.5%, with one discount point ($3,000) and $1,200 in lender fees.
| Interest rate | 6.500% |
| Monthly payment | $1,896.20 |
| Prepaid finance charges | $4,200 |
| Amount financed | $295,800 |
| APR | 6.636% |
The payment comes from the 6.5%. The 6.636% exists because you are making that payment while having received only $295,800 of usable money.
When the comparison breaks
The APR assumes you keep the loan for its full term. Nearly nobody does. The median mortgage is paid off — through a sale or a refinance — in well under half its term, and every year you shave off the holding period makes those up-front fees more expensive in annualized terms, not less.
So a lower APR is genuinely better if the two loans have the same term and you will actually hold them that long. Otherwise the APR quietly favors the offer with more money paid at closing, which may be exactly the wrong answer for someone who plans to sell in four years.
The honest comparison for that borrower isn’t APR at all — it’s total cost over the horizon they expect, which is what comparing two offers side by side is for.
Two more traps
Different lenders classify fees differently. The rules on what counts as a finance charge have judgment calls in them. Two lenders quoting the same rate and charging the same dollars can disclose slightly different APRs.
On adjustable-rate loans the APR is a forecast. It assumes today’s index holds for thirty years. Comparing the APR of an ARM against that of a fixed-rate loan compares a measurement to a guess.