Credit Card Daily Interest Calculator (Daily Periodic Rate)
See the daily periodic rate typically derived from your APR, and how many dollars that adds up to per day and per billing cycle.
Updated · Published · Built by Ali Ahmad, Founder
Calculation method: This calculator applies a daily periodic rate (APR ÷ 365, or 360 if selected) to the average daily balance you enter. Issuers' exact methods vary (compounding, grace periods, fees), so your actual statement may differ. See our methodology.
Credit Card Daily Interest Calculator
To calculate daily interest on a credit card, divide your APR by 365 (some cards use 360) to get the daily periodic rate, then multiply it by your balance. A 24.99% APR is about 0.0685% a day, or about $1.37 a day on a $2,000 balance. For a whole billing cycle, multiply the daily rate by your average daily balance and the number of days in the cycle.
Many issuers don't apply your APR directly. They use a small daily slice of it, applied to your balance each day of the billing cycle. This calculator shows that daily rate and an estimate of what it costs.
How the Calculator Works
Enter your APR, your average daily balance, the number of days in your billing cycle, and whether your issuer uses a 365- or 360-day year. The calculator returns:
- Daily periodic rate: APR ÷ 365 (or 360).
- Interest per day: average daily balance × daily rate.
- Interest this billing cycle: interest per day × days in cycle.
- Effective APR with daily compounding: (1 + daily rate)365 − 1.
Unlike the site's payoff calculators, this one uses the daily method rather than the simplified monthly model.
Formula
Cycle Interest = Average Daily Balance × Daily Periodic Rate × Days in Cycle
Effective APR = (1 + Daily Periodic Rate)365 − 1
This is an estimate. Issuers differ in how they compound (daily vs. once per cycle), which balances they include, and how they round, so your statement may differ.
Daily Interest Rate by APR
A credit card's daily interest rate is its APR divided by 365 (or 360 on some cards): a 20% APR is a daily rate of about 0.0548%, or about 55 cents a day for every $1,000 you owe.
| APR | Daily rate (APR ÷ 365) | Daily rate (APR ÷ 360) | Interest per day on $1,000 |
|---|---|---|---|
| 15% | 0.04110% | 0.04167% | $0.41 |
| 18% | 0.04932% | 0.05000% | $0.49 |
| 20% | 0.05479% | 0.05556% | $0.55 |
| 22% | 0.06027% | 0.06111% | $0.60 |
| 25% | 0.06849% | 0.06944% | $0.68 |
| 28% | 0.07671% | 0.07778% | $0.77 |
| 30% | 0.08219% | 0.08333% | $0.82 |
To get the daily interest on your own balance, multiply it by the daily rate. For example, $2,500 at 22% APR is $2,500 × 0.0006027 = about $1.51 a day, or about $45 over a 30-day billing cycle.
Example: 24.99% APR, $3,000 average daily balance, 30-day cycle
| Day-count basis | Daily periodic rate | Interest per day | Interest for 30 days |
|---|---|---|---|
| 365 days | 0.06847% | $2.05 | $61.62 |
| 360 days | 0.06942% | $2.08 | $62.48 |
With daily compounding over a full year, a 24.99% APR works out to an effective rate of about 28.38%.
How to Find Your Average Daily Balance
Add up your balance at the end of each day in the cycle and divide by the number of days. If you owed $2,500 for 10 days and $3,250 for 20 days of a 30-day cycle: (10 × $2,500 + 20 × $3,250) ÷ 30 = $3,000. A payment made early in the cycle lowers the average for more days than the same payment made just before the due date.
When the Result May Differ
This calculator uses the daily method, but your statement can still differ because of:
- Fees: annual, late, foreign-transaction, cash-advance, and balance-transfer fees aren't included unless the calculator asks for them.
- Grace period: whether new purchases accrue interest depends on whether you pay your statement balance in full and on your card's terms.
- Different APR categories: purchases, balance transfers, cash advances, and penalty APRs can carry different rates on the same card, and how payments are allocated between them affects the total.
- Compounding method: some issuers add each day's interest to the balance (daily compounding); others total it at the end of the cycle. This calculator shows simple daily interest for the cycle.
- Which balances count: whether new purchases are included in the average daily balance depends on your card's terms and grace period.
- Rounding and minimum interest charges: issuers may round daily rates or charge a minimum interest amount.
To compare a real statement with this formula, use the Interest Charge Checker. Your statement and cardholder agreement are the final word. See our methodology for how every calculator on this site works.
See the Bigger Picture
For a month-by-month payoff estimate (using the simplified monthly model), use the Credit Card Interest Calculator. For a dollars-per-month view of your APR, try the Credit Card APR Calculator.
Frequently Asked Questions
How do I calculate the daily periodic rate?
Divide your APR by 365 (some cards use 360). A 24% APR gives a daily periodic rate of about 0.0658%. Multiply that by your average daily balance and by the number of days in the billing cycle to estimate the interest charged.
Why does my issuer use a daily rate instead of a monthly one?
A daily rate reflects a balance that changes day to day as purchases and payments post. Averaging those daily balances captures the timing of each transaction, rather than using a single snapshot.
Does my card use 365 or 360 days?
Many use 365, but some use 360, which produces a slightly higher daily rate. Your cardholder agreement or statement usually shows the daily periodic rate or explains how it's calculated.
What is an average daily balance?
It's the sum of your balance at the end of each day in the billing cycle, divided by the number of days. Payments made earlier in the cycle lower it more than the same payment made near the end.
Why is the effective APR higher than my stated APR?
When interest compounds daily, you pay interest on previous interest. At 24.99% APR, daily compounding works out to an effective annual rate of about 28.4%.
Why doesn't my result match my statement?
Issuers differ in whether they compound daily or total interest per cycle, which balances they include (for example, new purchases while you have a grace period), rounding, and minimum interest charges. Treat the result as an estimate.
This calculator provides estimates for educational purposes only and is not financial, tax, or legal advice. Most results use a simplified monthly-interest model (APR ÷ 12); your card issuer may use a daily periodic rate and average daily balance, plus its own fees and grace period rules, so your actual figures may differ — always confirm against your official statement.
Sources
- What is a grace period for a credit card? — Consumer Financial Protection Bureau. Checked September 25, 2026.