Every credit card statement has a line that says something like "minimum payment due: $87." It looks small and manageable. That's the problem. It's designed to be the smallest amount the card company can legally ask for, not the amount that gets you out of debt in a reasonable time.
Most issuers calculate the minimum as roughly 1% of your current balance plus that month's interest, with a dollar floor, often around $25. The Consumer Financial Protection Bureau explains this formula in plain terms on its own site. The key detail most people miss: as your balance goes down, the minimum goes down too. That means the payment never really speeds up on its own. It just shrinks along with the debt, stretching the payoff out for years.
A real example: $3,000 at 22% APR
Let's use real numbers instead of talking in the abstract. Say you have a $3,000 balance on a card charging 22% APR, which is close to the average rate on cards that carry a balance. If you pay only the minimum every month, using the 1%-of-balance-plus-interest formula, here's what happens: it takes 180 months, which is 15 years, to pay it off, and you pay $4,433 in interest along the way. That's more interest than the original balance.
Now change one thing. Instead of the floating minimum, pay a fixed $150 every month. Same $3,000 balance, same 22% APR. This time it's paid off in 26 months, about two years and two months, for $771 in interest. That's a difference of 154 months and roughly $3,662 in interest saved, just from picking a fixed number instead of letting the minimum float down with your balance.
You can run your own balance and APR through the credit card payoff calculator and see both paths side by side, with the exact month-by-month numbers behind them, not just the headline totals.
Flipping the question: "I want this gone by a date"
Sometimes the more useful question isn't "how long will my payment take," it's "what do I need to pay to be done by a date I pick." The calculator has a second section for exactly that, using the standard fixed-payment loan formula (the same math used for any amortizing loan). On the same $3,000 balance at 22% APR:
- Debt-free in 1 year: $280.78/month, $369 total interest
- Debt-free in 2 years: $155.63/month, $735 total interest
- Debt-free in 3 years: $114.57/month, $1,125 total interest
- Debt-free in 5 years: $82.86/month, $1,971 total interest
Notice the pattern: the faster plan always costs less in total interest, even though the monthly payment is bigger. That's the trade-off minimum payments hide from you. A slower payoff doesn't just take longer, it actively costs more money, because interest keeps compounding on a balance that's barely moving.
Why the minimum keeps shrinking
Here's the mechanic worth understanding. Say your minimum this month is 1% of your balance plus interest. Next month, if you paid exactly that minimum, your balance is a little lower, so 1% of it is a little smaller, and the minimum due shrinks a bit too. It's a moving target that's always chasing your balance down, never pulling ahead of it. A fixed payment doesn't have that problem. It stays the same dollar amount every month, so as interest accrues less (because the balance is shrinking faster), a bigger share of each payment goes toward principal instead.
What this doesn't account for
This math assumes no new charges get added to the card after you start paying it down. If you keep using the card while paying it off, the balance (and the time it takes) resets upward every time you add a purchase. It also assumes a single fixed APR for the whole period. If you have a 0% promotional balance transfer, your real numbers will look much better while the promo lasts, then worse once it reverts to the normal rate. Run the numbers again with your actual promo rate and term to see the real picture.
It also doesn't tell you whether a $150/month payment, or whatever number you land on, actually fits your budget. That's a separate question this calculator can't answer for you. What it can do is show you exactly what each choice costs, in months and in dollars, so you're deciding with real numbers instead of a vague sense that "minimum payment" sounds responsible.
The one-sentence takeaway
Paying only the minimum on a credit card is the single most expensive way to carry a balance, not because the interest rate changes, but because the payment schedule is built to stretch out as long as possible. Picking any fixed payment above the minimum, even a modest one, cuts both the time and the total interest dramatically. Try your own balance on the credit card payoff calculator and see exactly where your number lands.
Source: the minimum payment formula used here (about 1% of balance plus interest, floored at $25) is described by the Consumer Financial Protection Bureau. Individual card agreements vary, check your own card's terms for its exact formula.
This is an educational estimate, not financial advice. See the disclaimer for more.
More money math in my book. Check out Money Math for Your 20s.