Credit Card Interest Calculator
| Balance | 30 days @ 22% | 1 year @ 22% |
|---|---|---|
| $1,000 | $18 | $220 |
| $2,500 | $45 | $550 |
| $5,000 | $90 | $1,100 |
Card interest is computed one day at a time: the daily periodic rate - the APR divided by 365 - applied to your balance for every day it rides. A $2,500 balance at 22 percent APR accrues about $1.51 a day, $45 over a carried month, $550 over a year. The calculator runs your own balance, rate and days so the number on the statement stops being a mystery.
The lever that matters is the grace period - CFPB defines it as the stretch between the end of the billing cycle and the payment due date. Pay the statement balance in full by that date and new purchases typically carry no interest at all; carry any part of the balance and the grace period usually drops, which means interest starts running on new purchases from the day you make them. That switch, more than the APR itself, is what separates a free card from a $550-a-year card.
How to use
- Enter the balance you expect to carry, the card's purchase APR and roughly how many days it will ride - the interest updates as you type.
- Read the daily rate line: that is the APR over 365, the exact dial your issuer turns every midnight on a carried balance.
- Compare the carried month against the year row, then check whether paying the full statement by the due date would zero the whole thing via the grace period.
Frequently asked questions
What is a grace period on a credit card?
CFPB's definition: the period between the end of your billing cycle and the date your payment is due. Inside that window, paying the statement balance in full means new purchases typically accrue no interest at all - the card effectively floats you for up to about a month, free. Lose it, usually by carrying a balance, and interest starts on new purchases from the transaction day.
I paid my bill in full - why was I still charged interest?
Because the grace period had already been lost the month before. When a balance carries, interest accrues daily and keeps accruing until a statement balance is paid in full - so the next statement includes interest from the start of that cycle even though you paid everything the notice showed. CFPB's guidance covers exactly this: pay in full by the due date and you generally cannot be charged interest that cycle; the catch is paying in full again the next cycle to restore the grace.
What is a daily periodic rate?
The APR divided by 365 - a 22 percent card runs about 0.0603 percent per day. Issuers multiply it by your average daily balance each day in the cycle and bill the sum. It is the same math this calculator runs, just revealed at statement time instead of up front.
Does making only the minimum payment cost interest?
Yes, and it does double duty: interest accrues on the carried portion every day, and the grace period on new purchases typically disappears while any balance remains - so new coffee purchases start accruing from the day you tap. The CARD Act's statement disclosures show both the years-to-payoff and the interest cost of that path; this calculator gives you the same verdict in real time.