Credit Card Payoff Calculator

What a fixed payment does to a card balance

The worked example — a fictional $5,000 balance at 20% APR, paid at a fixed $150 a month — clears in 50 months (4 yr 2 mo) at a cost of $2,359.09 in interest, for $7,359.09 paid in all. Every figure on this page is computed when the page is built by the same tested engine that powers the calculator above; the balances, APRs, fees and payments in the examples are illustrative inputs chosen for the arithmetic, not quotes.

The engine's convention is the one behind the site's loan schedules: interest accrues monthly at the card's APR ÷ 12 on whatever balance remains, and payments land at the end of each month. In month one of Example A the balance is the whole $5,000, so the interest charge is $5,000 × 20% ÷ 12 = $83.33, and only $66.67 of the $150 payment reaches the balance — 55.6% of the first payment is interest. Month two starts from $4,933.33, so the charge falls to $82.22 and $67.78 reaches the balance. The shift repeats every month, which is why a balance under a fixed payment falls slowly at first and quickly at the end.

The first month's interest is also the floor. A payment at or below it can never reduce the balance, so the engine refuses it before the loop runs rather than counting forever. Asked to apply $80 a month to Example A, it returns its own message: That payment never pays the card off — the first month's interest alone is more. Pay more than $83.33 per month. Just above the floor the arithmetic is valid but slow: at $100 a month the engine counts 109 months (9 yr 1 mo) and $5,840.10 of interest — more than the original balance. The same card at 5 fixed payments:

The rows are not proportional. Doubling the payment from $150 to $300 more than halves the count: it goes from 50 months to 20, and the interest from $2,359.09 to $906.81, because each additional dollar removes balance that would otherwise have accrued interest in every later month. The engine takes one amount and holds it for every month of the payoff; a payment recalculated from the balance each month is outside the model.

What the engine computes, step by step

In the first mode the form hands your inputs to the payoff function, which validates them, runs the steps below in order, and returns a typed result or an explicit, human-readable error. The other two modes are described in their own sections below: the target-date mode calls the annuity function and then feeds its payment back through this loop, and the transfer mode runs this loop twice. In every mode the interface only formats what comes back; it never does arithmetic of its own.

1. Validation. The balance must be greater than zero, and the APR, payment, fee, intro period or month count must sit within the engine's supported range; anything outside returns an explicit, human-readable error instead of a number.
2. Monthly rate = APR ÷ 100 ÷ 12: 20% a year becomes 1.6667% a month. The payment must exceed the balance × that rate — $83.33 in Example A — or the function returns the message quoted above.
3. The loop. Each month the engine charges interest on the remaining balance, adds it to the running interest total and to the balance, subtracts the payment, and counts the month, until the remaining balance is too small to show at the cent. Nothing is rounded between months.
4. The result carries the month count, the total interest, and the total paid, which is the balance plus the interest. It is not months × payment: 50 × $150 would be $7,500.00, while the engine reports $7,359.09, because the last payment on Example A is only $9.09.

Solving for the payment instead

The second mode turns the question around: given the balance, the APR and a target number of months, what fixed payment lands on zero in exactly that month? The engine does not loop for this. It uses the standard annuity formula on the card's monthly rate — the same formula behind the site's loan payments. For Example A it returns $463.17 a month to clear in 12 months, $254.48 for 24 and $185.82 for 36. Halving the time less than doubles the payment, and doubling the time does not halve it: the interest accrued over the longer span is what fills the gap.

The calculator adds a third line in this mode, "Total interest on that plan", which it gets by feeding the payment back through the payoff loop. The two functions agree with each other: $254.48 a month into the loop returns 24 months and $1,107.50 of interest. At a 0% APR the formula would divide by zero, so the engine divides the balance evenly across the months instead — $208.33 a month over 24 months for Example A's balance.

If you hold several cards

This calculator models one balance. It has no field for a second card and does not order payments between balances. The Debt Payoff Calculator takes several balances, each with its own APR and minimum, under the same monthly convention and runs two orderings, smallest starting balance first and highest APR first, reporting the months and the interest of each; the guide Snowball vs avalanche, as the engine runs them sets out the rollover rule it follows. Neither tool recommends an ordering; each reports the months and interest the figures you enter cost under either, and the difference between them. The Personal Loan Calculator runs a fixed-rate loan under the same monthly convention; whether a loan's figures bear on a card balance is a question for the reader, not for the arithmetic.

Balance transfers: the fee decides

The third mode runs two payoffs with the same fixed payment and puts the costs side by side. The stay path is the payoff loop on the current card, unchanged. The transfer path starts by adding the transfer fee — a percent of the balance moved — to the balance itself, so the payments during the introductory months are clearing the fee as well as the balance; for those months the monthly rate is zero, and whatever remains when the intro period ends accrues interest at the post-intro APR ÷ 12. The savings figure is the stay path's interest minus the sum of the transfer path's fee and interest, so a negative figure means the transfer path cost more.

Example B moves a fictional $6,000 balance off a 22% card onto an offer with a 3% fee, 15 months at 0% and 18% afterwards, paying $250 a month on either path. The fee is $180.00, so the transfer path starts at $6,180.00. Over the 15 interest-free months the payments remove $3,750, leaving $2,430.00 when the intro period ends; from there the post-intro rate applies, and the card clears in 26 months (2 yr 2 mo) with $216.60 of post-intro interest, for a transfer cost of $396.60. Staying put, the same $250 clears the card in 32 months (2 yr 8 mo) with $1,979.05 of interest. The savings figure is $1,582.45, and the total paid falls from $7,979.05 to $6,396.60.

The fee cuts both ways. Example C is a fictional $2,000 balance at 15% APR paid at $400 a month: staying put clears it in 6 months with $78.50 of interest. On an offer with a 5% fee, 12 intro months and 18% afterwards, the fee is $100.00, and the transfer path clears in 6 months — inside the intro period, so it accrues $0.00 of interest. The savings figure is -$21.50, and the engine's fee-exceeds-benefit flag is set, which is what the calculator's headline reads when it reports that the fee exceeds the interest avoided: the balance clears quickly either way, so there was little interest for the 0% period to avoid.

A sanity check the engine passes: with a 0% fee, no intro period and a post-intro APR equal to the current one, the two paths are the same loop, and on Example A both report $2,359.09 of interest and a savings figure of $0.00. The same fixed payment is applied on both paths by construction, and a payment that covers the interest during the 0% months but not afterwards is refused with the engine's own message rather than reported as a payoff; the companion guide quotes it. Whether the stay figure or the transfer figure is the one to act on is not a question the arithmetic answers.

How to read the result

• Time, from my payment. The headline is "Debt-free in …", the month count rendered as years and months — 50 months appears as 4 yr 2 mo — counting every payment, including the final partial one. "Total interest paid" and "Total paid" follow, shown to whole dollars.
• Payment, from a target date. The headline is the payment to the cent — $254.48 / month for 24 months on Example A — followed by "Pays the card off in" and "Total interest on that plan" (from feeding that payment back through the payoff loop: $1,107.50 here).
• Balance-transfer comparison. The headline is "Transferring saves …" or "Transferring loses … — the fee exceeds the interest avoided", taken from the sign of the savings figure. "Staying put" gives the months and the interest on the current card; "After transfer" gives the months, the fee, the post-intro interest and their sum.

The Copy result button places a one-line summary of the result on your clipboard. Money is shown to the cent for payments and fees and to whole dollars for the interest and total-paid lines; internally every calculation keeps the full precision of IEEE-754 double-precision arithmetic, and nothing is rounded between steps. Your card issuer's figure may differ by a few cents depending on their rounding and day-count conventions — the difference is presentational, not an error.

Where the calculator stops

The limits are the engine's. It models one frozen balance under one fixed payment, compounding monthly at APR ÷ 12 — card issuers typically accrue daily, which differs slightly. It does not model new purchases, a minimum payment recalculated from the balance, annual or late fees, a promotional rate other than a single 0% intro period followed by one post-intro APR, or a payment that changes from month to month. Inputs are validated before any arithmetic runs: non-numeric, negative, infinite or out-of-range values return an explicit, human-readable error instead of a number. Both payoff loops are bounded; the transfer loop reports an explicit out-of-range error at its bound, and the fixed-payment loop stops counting there. The engine does not know your issuer's day-count or rounding conventions or anything about your account beyond the figures you type. And a correct calculation can still be the wrong calculation for your situation — choosing the right loan for a real-world decision is judgment we cannot automate. The methodology page sets out the conventions and the rounding policy, and the companion guide quotes the engine's range-limit refusal messages.

Frequently asked questions

Not financial advice: a general educational estimate using monthly compounding; card issuers typically accrue daily, which differs slightly. Values are processed locally in your browser and never transmitted. See the methodology page.