Connected debt and interest-rate workflow

v10.91 connects debt payoff, credit-card cost, loan comparison, APR/APY, effective-rate, weighted-rate, and hypothetical consolidation calculations while preserving every established historical canonical and calculation engine.

Compare assumptions, not offers

Results are deterministic browser-local math from the values you enter. They are useful for scenario comparison, but they are not a lender quote, approval decision, investment forecast, credit recommendation, or substitute for an account agreement.

How to use this Credit Card Interest Calculator

Estimate simple daily credit-card interest for a balance, APR, and number of days using an explicit day-count basis.

Enter, paste, upload, or choose the inputs shown in the tool above.
Adjust the available options for the result you need.
Review the output before copying, downloading, or using it elsewhere.

What this tool does

Estimate daily and period interest from a balance and APR while keeping issuer-specific average-daily-balance rules, fees, transactions, and grace periods outside the model.

Practical tips and limits

Treat the output as an estimate from the assumptions you enter. Real taxes, fees, rates, timing, and lender or account rules can change the real-world result.