Credit Card Interest Accrued Daily Calculator

Credit card interest accrued daily: estimate interest for any number of days

Credit card interest can feel unpredictable because it is typically calculated daily. Even when your APR is shown as an annual rate, your issuer converts it into a daily periodic rate and applies it to your balance over time. This calculator estimates how much interest accrues across a chosen number of days so you can see the cost of carrying a balance, the value of paying earlier, and how new charges change the outcome.

Use this when you want a practical estimate of interest between two points in time, such as from today until your next payment, across a billing cycle, or during a temporary cash-flow crunch. The core idea is simple: interest accrues each day on the balance that is effectively outstanding that day. If your balance changes during the period, daily interest changes too. That is why timing matters, not only the total amounts.

This page gives you two levels of detail without forcing complexity. If you only enter a balance, APR, and number of days, you get a quick estimate based on daily compounding on a constant balance. If you add an optional one-time payment and an optional new charge, the calculator estimates a more realistic daily path: your balance goes up on the charge day and down on the payment day, and interest is calculated day by day across those segments.

Assumptions and how to use this calculator

• APR is converted to a daily rate using either 365 or 360 days, depending on your selection and issuer practice.
• If you do not enter any optional payment or charge, the balance is treated as constant for the full period.
• If you enter a payment or charge day, it is applied at the start of that day for simplicity, which slightly affects the estimate.
• This calculator estimates interest accrued only, not fees such as annual fees, late fees, cash advance fees, or foreign transaction fees.
• Results are estimates and may differ from issuer calculations that use average daily balance rules, statement cutoffs, and transaction posting times.

Common questions

Why does the same APR produce different interest depending on timing?

Because interest is applied daily. Paying earlier reduces the balance sooner, lowering the amount that accrues interest on each remaining day. Likewise, making a new charge earlier increases the balance for more days, increasing total interest. Two people can have the same APR and the same total payments, but different timing can change the interest paid.

What is the daily periodic rate and how is it calculated?

The daily periodic rate is the APR divided by a day basis, usually 365 and sometimes 360. For example, a 24% APR divided by 365 is about 0.06575% per day. The calculator shows your estimated daily rate so you can sanity check what you are paying each day on a given balance.

Does this match how issuers use the average daily balance method?

It is close for many scenarios, but not identical. Issuers often calculate interest by summing daily balances across the billing cycle and multiplying by the daily rate. This calculator approximates that by computing daily interest across constant-balance segments, which captures the most important driver: balance changes over time. If you have many transactions, statement cutoffs, or delayed posting, your issuer total can differ.

What if I do not know the exact payment day or amount?

Leave optional fields blank and use the quick estimate. If you only have an estimate, enter it anyway and treat the result as a range. For example, run it once with a payment on day 7 and once with a payment on day 14 to see how much timing alone changes interest. That is often the most actionable insight.

When should I not use this calculator?

Do not use it for promotional 0% periods, deferred interest plans, or cards with unusual interest rules where interest is waived if you pay in full by a specific date. Also avoid using it to estimate cash advances, which often have higher APRs and additional fees. For those cases, you need a calculator that models the specific product terms.