A credit card minimum payment is usually the month's interest plus a small percentage of the balance — 1% is common — or a flat percentage of the balance, with a dollar floor underneath. Because the amount is recalculated from a falling balance, the payment falls every month too, and a balance that looks manageable can take well over a decade to clear. The Credit Card Minimum Payment Calculator runs your issuer's formula month by month; this guide explains the machinery inside it.
The two formulas issuers actually use
No law sets your minimum at a particular dollar figure — your card agreement does. Across the major US issuers, two formulas dominate:
- Interest plus a percentage of the balance. The most common structure: this month's interest, plus a slice of the balance — 1% is the standard slice. By construction the payment always covers the interest and retires that slice of principal, so the balance always falls — just slowly.
- A flat percentage of the balance. Typically 2–4% of what you owe, with interest effectively paid out of it first. This version can fail outright, as the last section of this guide shows.
Underneath both sits a floor, usually $25 or $35: when the formula amount drops below the floor, you pay the floor instead. The floor is why the end of a minimum-only payoff finally accelerates — the last stretch is paid at a fixed $25 a month rather than at 1% of a small balance. The one exception is the final payment itself, which is simply whatever balance plus interest remains, even if that is less than the floor.
Why the payment shrinks every month
The minimum is a percentage of a balance that is itself falling, so every payment is a little smaller than the one before — and a smaller payment retires less principal, so the balance falls more slowly, so the next payment shrinks again. Nothing on the statement announces this loop; each month's bill looks almost identical to the last. It is only visible when the months are laid end to end, which is exactly what a month-by-month simulation does. The assumptions behind the example below are the ones the simulation states openly: no new purchases, no fees, and an APR that never changes. Any of the three, in real life, stretches the timeline further.
Worked example — $3,200 at 22.99% APR, minimums only
Daniel owes $3,200 at 22.99% APR. His issuer's minimum is the month's interest plus 1% of the balance, with a $25 floor. He makes no new purchases. The first two months show the mechanism:
- Month 1 interest: $3,200 × 22.99% ÷ 12 = $61.31
- Month 1 minimum: $61.31 + 1% of $3,200 ($32.00) = $93.31 — of which exactly $32.00 touches principal, leaving $3,168.00
- Month 2 minimum: $60.69 interest + $31.68 (1% of $3,168.00) = $92.37 — smaller already, leaving $3,136.32
Run that loop to the end (the simulation carries the unrounded payment, $93.3067… in month one, and the $25 floor takes over late in the schedule when the formula amount falls below it):
- Payoff time: 188 months — 15 years, 8 months
- Total interest: $5,040.51 — more than the $3,200 he borrowed
- Total paid: $8,240.51; final payment $10.89
Now the comparison that makes the structure visible. If Daniel simply keeps paying that first month's amount — the frozen minimum, $93.31 a month, no new money beyond what month one already asked of him — the same balance clears in 57 months with $2,061.95 of interest: $2,978.56 saved and 131 months sooner. Adding $50 a month on top of the shrinking minimum does better still — 47 months and $1,401.17 of interest. The debt never changed; only the payment's refusal to shrink did.
Try it with your own numbers
This mini-calculator is prefilled with the worked example above and runs the same month-by-month simulation as the full tool, in the interest-plus-a-percentage mode. The full calculator also runs the flat-percentage mode, the frozen-minimum comparison, and an extra-payment comparison.
Result
—
| First minimum payment | — |
| Final payment | — |
| Total interest | — |
| Total paid | — |
Open the full calculator — the Credit Card Minimum Payment Calculator runs the complete version of this calculation.
When a minimum payment never pays the card off
The flat-percentage formula has a failure mode the interest-plus formula cannot reach. Interest for one month is the APR divided by 12, expressed against the balance: at 27.99% APR that is about 2.33% of the balance, every month. A flat 2% minimum is smaller than that — the whole payment goes to interest, the shortfall is added to the balance, and the balance grows while every payment is made on time. There is no payoff date for that combination, and any tool that prints one is inventing it. The fix is a fixed payment sized to a deadline instead — a payment that clears a given balance in three or five years is a standard amortization calculation, and it is the rescue figure the minimum-payment tool shows for exactly this case.
One card or several: where the minimum fits a payoff plan
Paying every card's minimum is the floor of any payoff plan, not the plan itself. The plan is what happens to the money above the minimums: concentrating it on one card at a time retires balances years sooner than spreading it thin, and the choice of which card goes first — smallest balance or highest APR — is the comparison the Debt Snowball vs Avalanche Calculator runs on your real balances. Compounding, meanwhile, runs in both directions: the same mathematics that stretches a card balance across fifteen years is what grows a savings balance, and the APY Calculator shows that side of it — the effective yield a deposit earns once its own compounding is counted.
For educational and planning purposes only — not financial advice. This guide explains the standard minimum-payment formulas with a simplified simulation (monthly interest at APR ÷ 12, no new purchases, fees, or rate changes); issuers figure interest on daily balances and define their formulas in your card agreement, so your statement figures will differ. It is not professional financial advice. Verify your formula, floor, and balance against your card agreement and your lender's statements, and if minimum payments are all you can manage, a nonprofit credit counselor can review your options.