Minimum Payment Credit Card Trap Calculator

Why minimum-only payments take so long

Credit-card minimum payments are typically calculated as a small percentage of the outstanding balance — commonly cited ranges in consumer-credit literature put this in the low single digits, with a fixed-currency floor (often somewhere around 25 in the local currency) below which the percentage stops applying. Because the percentage minimum scales down as the balance falls, the principal-reduction component of each payment shrinks too, which extends the payoff term considerably. On a high-rate card, much of the payment ends up servicing interest rather than reducing principal — the calculator surfaces how long the resulting payoff actually takes.

How to use it

Enter the current balance, the card's APR, and the minimum-payment percentage from the cardholder agreement. The calculator simulates month-by-month payments at the minimum and returns the time to pay off, the total amount paid, the total interest, the interest as a percentage of the original balance, and the minimum-payment floor it applied. The currency selector at the top of the calculator changes formatting throughout — the math itself is currency-neutral.

Worked example

Picture a balance of 5,000 in the selected currency, at 22% APR with a 2% minimum-payment percentage (currency follows the selector). The calculator simulates each month: interest is added, then a payment equal to max(2% of balance, the currency floor) is applied. With a 0.5%-of-original-balance floor (25 on a 5,000 balance), the simulation runs out to about 80 years and 8 months. Total paid over that period is around 48,419, of which about 43,419 is interest — close to 868% of the original balance. The 80-year figure is the model's mathematical answer; in practice no card account stays open this long, but the simulation illustrates how steep the trade-off is when only minimums are paid.

How the math works

Iterative month-by-month simulation rather than a closed-form formula. For each month: interest = balance × monthly rate (annual ÷ 12 ÷ 100); payment = max(balance × minimum percentage ÷ 100, floor); balance = balance + interest − payment. The loop continues until the balance reaches zero (capped at 1,200 months for safety). The closed-form amortisation formula doesn't apply here because the payment isn't fixed — it changes each month as the balance changes. The floor is set at 0.5% of the original balance (≈25 on a 5,000 balance, scaling proportionally to other amounts), approximating the fixed-currency minimum payment most card issuers apply. On small starting balances (a few hundred or less in the selected currency), the proportional floor used here can underestimate real-world issuer minimums, which are typically a fixed currency amount around 25 in USD/GBP/EUR magnitudes regardless of balance size.

Where the inputs come from

The balance is on the most recent statement. The APR is the purchase APR shown in the cardholder agreement (separate from balance-transfer or cash-advance APRs, which can differ). The minimum-payment percentage is set out in the agreement and disclosed on each statement. Some agreements state a percentage and a fixed-currency floor; some use "interest plus 1%" or similar formulations. Where the agreement is unclear, the issuer's customer-service line can confirm the formula used on the specific account.

What this calculator doesn't capture

The model assumes a constant APR, no new spending on the card, no fees beyond the stated rate, and the percentage-plus-floor minimum-payment formula. Real card accounts can include penalty APR after a missed payment, late-payment fees, balance-transfer or cash-advance segments at different APRs, promotional rates that reset, payment-protection insurance products, and country-specific consumer-protection rules around minimum-payment disclosure. The figure functions as a baseline showing the structural problem with minimum-only payments rather than a precise prediction for any specific card account.

Even small overpayments compress the timeline

The math is sensitive to how much principal is reduced each month. Adding a small fixed amount on top of the minimum (say, an extra 25 or 50 a month) often cuts the payoff term by a meaningful proportion because every extra unit lands directly on principal — there's no interest taken out of it because it isn't a charge against the existing balance. The Credit Card Interest Paydown Simulator on this site can model that scenario directly with a fixed extra-payment input.