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.
Credit Card Interest per Month by Balance and APR
Approximate interest for one month if you carry the balance and make no new purchases:
| Balance | 18% APR | 22% APR | 25% APR | 29% APR |
|---|---|---|---|---|
| $1,000 | $15.00 | $18.33 | $20.83 | $24.17 |
| $2,500 | $37.50 | $45.83 | $52.08 | $60.42 |
| $5,000 | $75.00 | $91.67 | $104.17 | $120.83 |
| $10,000 | $150.00 | $183.33 | $208.33 | $241.67 |
Card issuers actually charge interest daily, so a 31-day billing cycle costs slightly more than this and a 28-day cycle slightly less.
From APR to Monthly Interest, Step by Step
Interest for the cycle = Average daily balance × Daily rate × Days in cycle
Example: A $3,000 balance at 24.99% APR. The daily rate is 24.99% ÷ 365 = 0.0685%. Over a 30-day billing cycle the interest is $3,000 × 0.000685 × 30 = $61.62.
Some issuers divide by 360 instead of 365, which makes the daily rate a little higher. Your card agreement states which one is used.
How the Average Daily Balance Method Works
Most US card issuers charge interest on the average daily balance — the balance at the end of each day, averaged over the billing cycle — rather than on your statement balance.
Example: You carry $2,000 for the first 15 days of a 30-day cycle, then pay $1,000 and carry $1,000 for the last 15 days. Your average daily balance is $1,500, so at 24.99% APR the interest is $1,500 × 0.000685 × 30 = $30.81. Had you paid the $1,000 on day 1 instead, the interest would be about $20.54.
That is why paying early in the cycle — not just before the due date — lowers your interest.
How to Pay Less (or No) Credit Card Interest
- Pay the full statement balance by the due date. Most cards then give you a grace period of at least 21 days on new purchases, so you pay no interest at all.
- Pay early and more than once a month. Every extra payment lowers your average daily balance.
- Move the balance to a 0% intro APR card. Transfer fees are usually 3–5%, which is often far less than a year of interest.
- Ask your issuer for a lower APR. Cardholders with a good payment history are often offered one.
- Avoid cash advances. They usually carry a higher APR and start charging interest immediately, with no grace period.
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.