What the calculator shows
Enter balance, annual purchase rate, fixed monthly payment and planned new monthly charges. The result shows payoff months, total interest and total paid, plus an indicative minimum-payment path when new charges are zero.
Calculation method
Each month adds balance × annual rate ÷ 12 and new charges, then subtracts the fixed payment. The final payment falls to the amount due. The comparison path uses the greater of $35 or monthly interest plus 1% of balance as an indicative minimum.
Inputs to confirm
Use the statement balance, applicable APR and issuer minimum-payment formula. Promotional rates, cash advances and balance-transfer fees can be added as separate scenarios using the relevant balance and rate.
Worked fixed-payment example
A $6,500 balance at 22.15% with a fixed $250 payment and no new charges takes an estimated 36 months, with $2,436.53 interest and $8,936.53 total paid. The indicative minimum path lasts much longer because its dollar payment generally falls with the balance.
| Change | Balance direction | Likely consequence |
|---|---|---|
| Add $100 new monthly charges | Falls more slowly or may rise | Later or impossible payoff |
| Raise fixed payment | Falls faster | Less interest and fewer months |
| Lower promotional rate | Falls faster while rate lasts | Recalculate when promotion ends |
A payoff plan works only when the balance falls
Interest is added before the fixed payment in each model month. If the payment does not exceed interest plus new charges, a credible payoff date does not exist, so the calculator shows the amount needed to begin reducing the balance.
Fixed payments and minimum payments create different paths
Keeping a fixed dollar payment after the balance falls usually repays principal faster. The comparison minimum is only an illustration; issuers can use percentages, floors, fees and past-due amounts that produce a different statement minimum.
Purchase APR is not the only possible card rate
Cash advances, balance transfers, promotional balances and penalty pricing may each use different rates and fees. The model applies one entered annual purchase rate to the whole balance and approximates monthly interest rather than daily average balance.
Use statement data to make the scenario actionable
Enter the balance and rate applying to that balance, keep new charges realistic and choose a payment affordable every month. Compare the result with the issuer’s payoff disclosure, minimum-payment warning and promotional expiry dates.
| Check | Why it matters | Where to find it |
|---|---|---|
| APR by balance type | Different balances may accrue differently | Statement rate table |
| New charges | Can prevent the balance falling | Budget and recent statements |
| Minimum and fixed payment | Changes payoff time and interest | Statement and chosen plan |
Primary source
Federal Reserve G.19: credit-card accounts assessed interest