Credit Card Interest Calculator
See exactly how much your balance is costing you — in dollars, per day and per month — based on your real APR.
Calculate Your Interest
How Credit Card Interest Is Calculated
Credit card issuers don't charge interest once a month the way a loan does — they calculate it daily, using a daily periodic rate, then add it up over your billing cycle.
Monthly interest ≈ Balance × (APR ÷ 12)
Daily interest = Balance × Daily rate
Worked example: A $2,000 balance at 24.99% APR costs about $1.37 a day, or roughly $41.65 in a single month — before you've spent another cent.
Paying Slow vs. Paying Fast
| $50/month | $150/month | |
|---|---|---|
| Time to pay off | 87 months (7.3 yrs) | 16 months (1.3 yrs) |
| Total interest | $2,350 | $400 |
On the same $2,000 balance at 24.99% APR, tripling the payment doesn't just pay it off five times faster — it saves nearly $2,000 in interest. Near the interest-only amount (about $41.65/month here), almost your entire payment goes to interest instead of principal, which is why low fixed payments drag on for years. Use the Payoff Calculator to test any payment amount against your own balance.
Frequently Asked Questions
How is credit card interest calculated if I pay part of my balance mid-cycle?
Most issuers use your average daily balance across the billing cycle, not just your balance on the statement date. Paying earlier in the cycle lowers your average balance and therefore your interest charge.
Does interest still apply if I pay before the due date?
If you carried a balance from the previous cycle, yes. Interest only stops accruing entirely if you pay your statement balance in full by the due date every cycle.
What's the difference between APR and interest rate on a credit card?
For credit cards they're almost always the same number. This differs from loans, where APR can include extra fees on top of the base interest rate.
Why did my interest charge go up even though I didn't spend more?
Usually because your average daily balance went up — for example if you paid later in the cycle than last month, or a large purchase posted early.