Daily interest calculator
What this balance costs per dayworked example
$4.11/day
- Daily periodic rate
- 0.06847%APR / 365
- Total over 30 days
- $123.24
- Per 30 days
- $123.24
At 24.99% on a 365-day basis, $6,000 accrues $4.11 of interest every day — $123.24 over 30 days. Issuers apply the daily rate to your average daily balance and compound daily, so a real statement can differ by cents over one cycle; money that arrives mid-cycle lowers the average daily balance, which is why paying earlier in the cycle costs less than waiting for the due date.
What a balance costs per day: the daily periodic rate, the dollars of interest each day adds, and the total over any number of days. The per-day figure is the most motivating number in debt math — it turns an abstract APR into what this morning cost.
How to use this calculator
- 1
Enter the balance you want to see the cost of
This tool answers one question: what does carrying this cost per day? Use whichever balance you are actually thinking about — a whole card, or the part of it you are about to pay off.
- 2
Check whether your agreement uses 365 or 360 days
Most card issuers divide the APR by 365; some loan contracts use 360, which makes each day slightly more expensive at the same APR. The toggle is there because the difference is real and your agreement states which applies.
- 3
Use the per-day number as a timing argument
Interest is charged on your average daily balance, so money that arrives mid-cycle lowers that average for the rest of the days. The per-day figure is what paying on payday instead of on the due date is worth.
- 4
Expect a small gap against your statement
Your balance moves during the cycle and issuers compound daily, while this shows simple per-day interest on a fixed balance. Over one cycle the difference is cents — it is a perspective tool, not a statement reproduction.
- Monthly interest accrualconvention — interest per month = balance x (APR / 12). Verified against CFPB — How does my credit card company calculate the amount of interest I owe? (issuers compound daily on the average daily balance, so a real statement can differ by a few dollars)
Everything you type here is computed in your browser. Nothing you enter is stored on a server, sent anywhere, or shared — there is no account, and your balances never leave your device.
Frequently asked questions
How do card issuers calculate daily interest?
Why does my statement interest differ slightly from daily rate × 30?
What is the 365 vs 360 day basis?
What is the per-day number useful for?
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