Credit Card Interest Calculator
Estimate a card’s first-month interest and payoff cost at a fixed payment. Issuer statements may use daily balances and grace-period rules that differ from this monthly approximation.
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Written by the ToolGrym Editorial Team
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Calculation workspace
Enter your numbers
No submit button — results update as you type.
First-month interest
$166.60
54 months at a fixed payment
- Total interest to payoff
- $5,316
Planning context
54 months
Use official rules and your documents to confirm
Educational planning math only. Rules, eligibility, tax treatment, benefit formulas, and lender or agency calculations can differ from this simplified estimate.
Read how credit-card interest is calculated and compare with the credit-card payoff calculator.
Frequently asked questions
- How is the first-month estimate calculated?
- It multiplies the balance by APR divided by 12. Your issuer may use an average daily balance and a daily periodic rate.
- Why does payment size matter?
- A payment that barely exceeds interest reduces principal slowly and can extend the payoff timeline.
- Does this include new purchases?
- No. Enter the current balance and a fixed monthly payment without adding new charges.
- Is APR the same as the rate on my statement?
- Use the purchase APR for a simple estimate. Cash-advance, penalty, promo, and balance-transfer APRs can differ.
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The ToolGrym editorial team builds and maintains every calculator on this site. Each tool’s formulas are implemented as tested code and verified against authoritative sources such as the CFPB, Federal Reserve, IRS, and BLS.