How do I find the interest rate on my credit card?

To find the interest rate on your credit card, look at your cardmember agreement and your monthly credit card statements. Your interest rate will be there in the form of an annual percentage rate (APR). But as “annual” implies, an APR is the cumulative interest rate for a whole year, which isn’t all that helpful for calculating actual interest charges from day to day or month to month.

You can figure your daily interest rate – or daily periodic rate – by dividing your APR by 365 (days in a year) because credit card interest compounds daily. (It’s worth noting that some card issuers may divide by 360 rather than 365). This calculation will give you the actual daily rate at which you accrue interest on a card. If your APR is 19.99%, your daily periodic rate would be 0.0547%.

The terms APR and interest rate are often used interchangeably. For general purposes, they express the same idea, though you’ll get a much better sense of your actual “interest rate” by using the daily periodic rate.

It’s worth noting that most credit card rates change (indicated in terms by a V next to your APR). So if the so-called prime rate that credit card APRs are tied to goes up, your rate will rise, too. A credit card agreement may note that the account’s APR is the prime rate plus a certain fixed percentage. Or, your rate might rise to a penalty APR (also found in credit card terms) if you miss a payment. Your card issuer must notify you of a rate change 45 days before it takes effect, unless you’re 60 days or more past-due on payment.

Though it’s good practice to keep an eye on your APR, interest rates don’t matter if you pay your credit card bill in full every month. If you aim to pay no interest, you won’t have to worry about crunching these numbers.