Credit card daily interest ledger calculator

The payment date changes the interest-bearing balance

This ledger applies each day’s net transactions before calculating that day’s interest. A payment therefore changes both the remaining balance and the interest for its payment date. Moving the same payment later can increase the cycle interest even if the final principal is unchanged.

Use positive amounts for new purchases and negative amounts for principal payments. Entries on the same date are netted. A payment that would create a credit balance is rejected because this simplified model does not calculate interest credits or issuer-specific allocation rules.

The Invoice overdue simple interest and payments calculator models principal payments after a due date under a separate overdue-day convention. Do not transfer a card grace-period or payment-allocation rule into that contract-rate model.

Accrued and capitalized interest are different

Simple daily accrual records each day’s finance charge separately and adds the total at cycle end. Daily capitalization immediately adds each charge to the balance, allowing it to contribute to subsequent interest. The two models are selectable because they are not interchangeable.

The average daily balance is calculated from the actual daily interest base used in the chosen model. With a constant simple daily rate, multiplying that average by the number of days and the daily rate reproduces the cycle interest.

Read the card agreement before comparing a statement

A real account may have different purchase and cash-advance rates, a grace period, fees and rules about which balance a payment reduces. The entered APR and denominator do not reconstruct those policies automatically.

This page avoids rounding daily charges to cents before totaling them. An issuer that rounds at a different step can show a different statement amount. Use the table to check the timing arithmetic, then reconcile any policy or rounding differences separately.

Work through the example

A 1,000 balance at a 36.5 percent nominal rate accrues 1 per day on a 365-day basis. A 500 payment before interest on day six makes a ten-day simple-accrual cycle cost 7.50.

Use the worked table to trace where each input enters. Then change one assumption and calculate again, leaving the others fixed. A comparison is easier to interpret when the change has one identifiable cause rather than a different set of measurements, dates and rates all at once.

What this model does not establish

No grace period, minimum-payment advice, multiple APR buckets, fees, issuer payment-allocation or statement-rounding reproduction. Inclusive cycle up to 367 days. Educational arithmetic from an entered rate and explicitly selected posting model.

Keep the input assumptions with any exported result. Illustrative values do not become observations merely because the output is precise. For a real purchase, financial reconciliation or technical decision, check the underlying records and applicable requirements before treating this scenario as a final answer.