Credit Card Interest Calculator
See exactly what a balance costs you per day, per billing cycle, and per year — using the daily periodic rate your issuer actually charges.
Short answer: credit card interest is charged daily, not monthly. At the U.S. average APR of 21.52%, the daily periodic rate is 0.05896%. A $5,000 balance therefore costs $2.95 a day, $88.44 over a 30-day billing cycle, and $1,076 over a year if the balance never moves. Pay your statement balance in full and purchases accrue no interest at all.
Average APR: Federal Reserve G.19, Q1 2026 (accounts assessed interest).
How you compare
Your APR vs. the U.S. average
How credit card interest is calculated
Card issuers do not divide your APR by 12. They convert it to a daily periodic rate — the APR divided by 365 — and charge that on your balance every day of the billing cycle:
interest = balance × (APR ÷ 365) × days in cycle
At 21.52% APR the daily periodic rate is 0.05896%. On a $5,000 balance that is $2.95 a day, or $88.44 over a 30-day cycle. Because interest compounds daily on most cards, a full year of carrying that balance costs slightly more than 12 cycles.
Interest for one 30-day cycle
| Balance | 15.0% | 18.0% | 21.52% | 24.99% | 29.99% |
|---|---|---|---|---|---|
| $500 | $6.16 | $7.40 | $8.84 | $10.27 | $12.32 |
| $1,000 | $12.33 | $14.79 | $17.69 | $20.54 | $24.65 |
| $2,500 | $30.82 | $36.99 | $44.22 | $51.35 | $61.62 |
| $5,000 | $61.64 | $73.97 | $88.44 | $102.70 | $123.25 |
| $10,000 | $123.29 | $147.95 | $176.88 | $205.40 | $246.49 |
Interest for a full year, if the balance never moves
| Balance | 15.0% | 18.0% | 21.52% | 24.99% | 29.99% |
|---|---|---|---|---|---|
| $500 | $75 | $90 | $108 | $125 | $150 |
| $1,000 | $150 | $180 | $215 | $250 | $300 |
| $2,500 | $375 | $450 | $538 | $625 | $750 |
| $5,000 | $750 | $900 | $1,076 | $1,249 | $1,500 |
| $10,000 | $1,500 | $1,800 | $2,152 | $2,499 | $2,999 |
Assumes the balance stays constant and no grace period applies. If you pay the statement balance in full each month, most cards charge no interest on purchases at all.
Common mistakes
- Dividing APR by 12. Issuers use a daily rate, so a 31-day cycle costs more than a 28-day one on the same balance.
- Assuming a grace period on cash advances or balance transfers — interest usually starts immediately.
- Paying only slightly more than the interest. At 21.52% a $5,000 balance accrues about $88 a cycle; a $100 payment leaves barely $10 toward principal.
Frequently asked questions
How is credit card interest calculated?
Issuers convert the APR to a daily periodic rate (APR divided by 365) and apply it to your balance each day of the billing cycle. At 21.52% APR the daily rate is 0.05896%. On a $5,000 balance that is $2.95 per day, or $88.44 over a 30-day cycle.
How much interest will I pay on $5,000 in credit card debt?
At the U.S. average APR of 21.52%, a $5,000 balance costs about $88.44 in interest for a 30-day billing cycle and about $1,076 over a full year if the balance never changes.
Does paying my statement balance in full avoid interest?
On purchases, yes. Most cards give a grace period of at least 21 days, so paying the statement balance in full by the due date means no interest on purchases. Cash advances and balance transfers usually accrue interest from day one, with no grace period.
Is a 21.52% APR high?
It is the U.S. average. The Federal Reserve's G.19 release put the average APR on credit card accounts assessed interest at 21.52% in Q1 2026. Rates below about 15% are low; above roughly 26% is very high.
Why did my interest change when nothing else did?
Billing cycles differ in length. Interest is charged per day, so a 31-day cycle costs about 11% more than a 28-day cycle on the same balance and APR.