Quick guide
How to use this calculator
- Enter the balances, rates, fees, and timing requested by the visible labels.
- Keep monetary entries in one consistent currency.
- Review the result together with the declared calculation convention and exclusions.
Calculation method
Calculation method
Interest = average daily balance × annual rate ÷ day-count basis × billing-cycle days.
Entered fixed decimals are aggregated exactly. Iterative rate solving is bounded to a single nonnegative monthly cash-flow root and fails explicitly if the result is absent, too large, or not reliably representable.
Worked example
Worked example
An average daily balance of 1,000 at 18% for 30 days on a 365-day basis produces about 14.79 of interest.
Interest = average daily balance × annual rate ÷ day-count basis × billing-cycle days.
Supported inputs
Precision and limits
Visible input limits
Amounts are capped at 1e12, rates at 1000%, monthly periods at 1,200, and fixed decimals at 12 places. List tools accept 1–20 uniquely named rows.
Estimate, not a disclosure
Results model only the entered convention. They do not reproduce a lender statement, credit score, underwriting outcome, or jurisdiction-specific consumer-credit disclosure.
International scope
No currency, country, credit bureau, scoring model, statutory APR rule, fee classification, grace period, or issuer policy is assumed.
Calculator-specific assumptions
This is an average-daily-balance estimate without within-cycle interest compounding. Issuers may use 360 or 365 days, multiple balances and rates, grace periods, minimum charges, daily compounding, and different transaction timing.