Daily Periodic Rate Calculator
See the exact daily rate your issuer applies to your balance, and how many dollars that adds up to per day, week, and billing cycle.
Last updated September 2026 · Reviewed by the CalcMyCard editorial team
Your daily periodic rate is your APR divided by 365 (or occasionally 360). Multiply it by your average daily balance and the number of days in your billing cycle to get the interest charged for that cycle.
The daily periodic rate is the number your issuer actually uses behind the scenes — not your APR directly, but a tiny daily slice of it, applied to your balance every day of the billing cycle. This calculator shows you that exact rate and what it costs you, day by day.
The formula, step by step
Take your APR and divide it by the number of days your issuer uses in a year (365 for most issuers, 360 for a few). That gives you the daily periodic rate as a small percentage. Multiply that rate by your average daily balance for the cycle, then multiply again by the number of days in the cycle, and you have your interest charge for that statement.
Why "average daily balance" matters
Your balance changes throughout the month as you make purchases and payments, so issuers don't apply the rate to a single snapshot — they average your balance across every day of the cycle. This means a large payment made early in the cycle saves you more interest than the same payment made right before the due date, because it lowers your average daily balance for more days.
Why this number is higher than it looks
Because interest compounds daily rather than monthly, the "effective" annual rate you actually pay is slightly higher than your stated APR — the calculator above shows this effective APR alongside the simple one. It's a small gap at typical rates, but it's a real one, and it's part of why credit card debt compounds faster than many people expect.
See the bigger picture
For a month-by-month view of exactly how this rate plays out on your real balance and payment plan, use the Credit Card Interest Calculator.
Frequently Asked Questions
How do I calculate the daily periodic rate?
Divide your APR by 365 (the number of days most issuers use, though a few 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 interest charged.
Why does my issuer use daily compounding instead of monthly?
Daily compounding lets the issuer capture interest on interest more precisely, and it reflects a balance that changes day to day as you make purchases and payments — using your average daily balance rather than a single snapshot.
This calculator provides estimates for educational purposes only and is not financial, tax, or legal advice. Your card issuer's actual calculation may differ slightly based on its compounding method, fees, and grace period rules — always confirm against your official statement.