Credit Card APR Calculator
Calculate total interest costs on credit card balances based on purchase APR, penalty APR, and daily periodic compounding.
What this calculator does
The Credit Card APR Calculator estimates your result instantly from the values you enter, using standard credit cards formulas. Calculate total interest costs on credit card balances based on purchase APR, penalty APR, and daily periodic compounding. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate for planning rather than financial advice.
About Credit Card APR Calculator
The Credit Card APR Calculator converts nominal purchase and cash advance APRs into actual dollar financing charges across customizable billing cycles.
Formula & Mathematical Calculation
Monthly Interest = Average Daily Balance × ( APR / 365 ) × Days in Cycle
Calculation Example
$4,500 Balance @ 26.99% APR (30 Days): Monthly Interest Charge = $99.82/month ($1,197.84/year).
Key Benefits
- Calculates exact monthly and annual interest charges
- Converts purchase APR to daily periodic interest rate
- Models cost of balance accumulation over time
- Highlights savings from low-rate personal loans
- Simple and free tool
How to Use this Calculator
-
Enter Balance
Input credit card balance. -
Enter APR %
Input annual percentage rate. -
Calculate Interest
Click Calculate to view financing cost.
Assumptions & Limitations
What the calculation assumes
- Every value you enter is treated as an exact, known amount.
- Rates and contributions are assumed to stay constant for the whole period unless the form asks for them separately.
- Results use standard financial formulas and ignore fees, penalties and promotional terms that are not entered above.
- Inflation, tax changes and market volatility are not modelled unless a field for them is provided.
- Amounts are unit-agnostic: results are returned in the same currency you enter.
What it does not cover
- Credit Card APR Calculator produces estimates for education and planning, not a quote, offer or professional advice.
- Real-world outcomes differ when fees, taxes, rounding rules or provider-specific terms apply.
- Local regulations and tax rules vary by country and change over time; verify current rules for your jurisdiction.
- Figures are only as accurate as the inputs you supply — check them before acting on the result.
- For decisions with lasting financial impact, confirm the numbers with a qualified professional.