Daily periodic rate

What it is

The daily periodic rate is your APR divided by the number of days in the year — the rate actually applied to your balance each day.

DPR = APR / 365

A 19.99% card has a daily periodic rate of 0.05477%. That figure is disclosed in your cardholder agreement and printed on most statements, usually beside the balance it was applied to.

Some issuers divide by 360 rather than 365, which produces a slightly higher daily rate. Regulation Z permits either; the agreement states which is used.

How your interest charge is built

Three steps, and the middle one is where the money is.

1. Find the average daily balance. The issuer records your balance at the end of each day of the billing cycle, adds them up, and divides by the number of days. A balance paid down mid-cycle therefore costs less than one paid on the last day — the timing of payments matters, not just the amount.

2. Multiply by the daily periodic rate.

3. Multiply by the days in the cycle.

So a $2,500 average daily balance on a 19.99% card over a 30-day cycle:

0.05477% × $2,500 × 30 = $41.08

Issuers differ on whether new purchases enter the average from their posting date, and a small number use a two-cycle average that reaches back into the previous month. The agreement specifies the method.

Daily compounding

Most issuers add each day’s interest to the balance, so the next day’s interest is charged on it too. Over a year, that compounding raises the effective cost meaningfully above the stated APR: 19.99% compounded daily works out to about 22.1% in real terms.

That difference is not hidden — it simply is not what the APR measures. Regulation Z requires lenders to disclose the periodic rate annualized by multiplication, not by compounding. The compounded figure is the APY, covered on APR vs APY.

Why it is worth understanding

The grace period beats all of it. Pay your statement balance in full and the daily rate is never applied to purchases. Every calculation above is a description of what happens once you carry a balance.

Paying early genuinely helps. Because interest is computed on a daily average rather than a month-end snapshot, a payment made on the 5th costs you less than the same payment on the 25th. Mid-cycle payments are one of the few ways to reduce a card’s cost without reducing what you spend.

Cash advances start immediately. There is no grace period on them, so the daily rate applies from the transaction date — typically at a higher APR, with a fee on top.

Check the arithmetic on your statement. Your statement lists the periodic rate, the balance it was applied to, and the resulting charge. It is a three-number calculation, and it is worth verifying once — particularly in the cycle after a promotional rate ends, which is where surprises cluster.