How this credit card payoff calculator works
A credit card balance does not come with a schedule the way a loan does. You choose how much to pay each month, and the card charges interest on whatever is left. That flexibility is exactly what makes card debt expensive: pay only the minimum and the balance barely moves, pay a fixed amount and it can vanish in a couple of years.
At a glance
- Interest is charged monthly on the remaining balance; the payment covers interest first.
- A fixed payment clears a card in a few years; the minimum can take decades.
- Target mode gives the exact payment for a payoff date.
- A payment at or below the first month's interest never reduces the balance.
This calculator simulates the balance month by month. Enter what you owe and the card's APR, then pick a plan: a fixed amount each month, paying off by a date (the calculator tells you the payment needed), or the issuer's minimum payment so you can see what happens if you do nothing more. A comparison line shows how much faster you would finish by paying a little extra.
The monthly arithmetic
interest = balance × (APR ÷ 12) principal = payment − interest new balance = balance − principal
Card issuers actually use a daily periodic rate (APR ÷ 365) on your average daily balance, which lands within a few cents of the monthly figure but depends on exactly when you pay. The monthly approach is what every payoff calculator uses and is accurate enough for planning.
Worked example: $200 a month
A balance of $5,000 at 18% APR, paying $200 a month.
Monthly rate: 18% ÷ 12 = 1.5%. Month 1 interest: 5,000 × 1.5% = $75.00. Principal repaid: 200 − 75 = $125, leaving $4,875.
Month 2 interest: 4,875 × 1.5% = $73.13, so $126.87 comes off the balance. Each month a little more of the $200 goes to principal.
The balance reaches zero after 32 payments (the last one is smaller), with $1,313.97 of interest in total. Paying $250 instead clears it in 24 months and saves about $330.
Why minimum payments are a trap
Most US cards set the minimum at a small percentage of the balance, often 1%, plus that month's interest and fees, with a floor around $25. Because the percentage part shrinks as the balance falls, the payment shrinks too, and the balance declines painfully slowly.
Worked example: paying only the minimum
Same $5,000 at 18%, minimum of 1% of the balance plus interest, never less than $25.
Month 1: 1% × 5,000 = $50 plus $75 interest = a $125 payment, of which only $50 reduces the debt. By the time the balance is $1,000 the payment is down to about $25.
The card is finally cleared after 222 months, over 18 years, with roughly $6,500 of interest, more than the original balance.
Your statement's "minimum payment warning" box shows a similar calculation, which is why it usually quotes decades. The fix is simple: choose an amount and keep paying it even as the minimum falls.
| Fixed monthly payment | Months to clear $5,000 at 18% | Total interest |
|---|---|---|
| $125 | 62 | $2,693 |
| $150 | 47 | $1,984 |
| $200 | 32 | $1,314 |
| $250 | 24 | $989 |
| $300 | 20 | $797 |
Paying off by a date
If you would rather set a deadline, the target mode uses the amortising-payment formula to find the fixed monthly amount that clears the balance in exactly that many months:
payment = B × r ÷ (1 − (1 + r)^−n)
To clear $5,000 at 18% in 24 months you need $249.62 a month; in 12 months, $458.40. The table shows every month so you can confirm the balance hits zero on schedule.
When a payment never works
If a payment is equal to or less than the first month's interest, the balance cannot fall. On $5,000 at 18% that threshold is $75: pay $75 and you tread water forever; pay $70 and the balance grows. The calculator shows a clear warning in this case and tells you the smallest payment that makes progress.
Strategies the numbers support
- Pay more than the minimum, and keep the amount fixed. The comparison line shows the effect of each extra $50.
- Highest APR first. If you carry several cards, run each through the calculator; put your extra money on the one with the highest rate and pay minimums on the rest. This "avalanche" minimises total interest.
- Consider a balance transfer carefully. A 0% promotional rate can save a lot, but the transfer fee (typically 3 to 5%) is added to the balance and the rate jumps when the promotion ends. Model it by entering the fee-inclusive balance at the promotional APR for the promotional months.
- Stop adding to the balance. The simulation assumes no new spending; every new purchase resets the clock.
What the calculator does not include
Annual fees, late fees, penalty APRs, and the daily-balance method issuers use. Promotional rates that change mid-plan need to be modelled in two steps. Rewards earned on new spending are irrelevant while you carry a balance, the interest dwarfs them.
Using the result
The months-to-payoff figure sets your expectation; the total interest is the price of taking that long. Try the comparison field with different extra amounts until the total interest feels acceptable, then set that payment up as an automatic transfer so the plan survives the months when you are not paying attention.