Credit Card Calculator Payoff Schedule and Interest

A credit card payoff schedule estimates how many monthly payments it may take to clear a balance, the payment amount, and the interest paid under the assumptions you enter. Enter your current balance, APR, and planned monthly payment to see an estimated payoff time and total interest; the schedule is an arithmetic illustration, not a statement from your card issuer.

Formula

The calculator treats the balance as accruing interest monthly at the APR divided by 12, with a fixed payment made at the end of each month. It estimates the number of whole monthly payments needed using:

n = ceil(round(−ln(1 − rB / M) / ln(1 + r), 6))

• B is the starting balance in dollars.
• APR is the annual percentage rate, entered as a percentage, such as 20 for 20%.
• r is the monthly rate: APR ÷ 1,200.
• M is the planned monthly payment in dollars.
• n is the estimated number of monthly payments, rounded up to a whole month.

Estimated total paid is M × n. Estimated interest is (M × n) − B. For clarity, those totals assume the same full payment in every month, including the final month; an actual final payment is often smaller because it pays only the remaining balance and interest. This calculator therefore gives an easy-to-compare fixed-payment estimate, not an exact issuer billing schedule.

Worked Example

Using the default inputs—balance $5,000, APR 20%, and monthly payment $250:

1. Convert APR to a monthly rate: 20 ÷ 1,200 = 0.0166667, or about 1.66667% per month.
2. Substitute into the payoff formula: −ln(1 − (0.0166667 × 5,000 ÷ 250)) ÷ ln(1.0166667). The unrounded estimate is about 27.69 months; rounding up gives 28 months.
3. Estimated total paid: $250 × 28 = $7,000.
4. Estimated interest: $7,000 − $5,000 = $2,000.

The calculator’s headline result is 28 estimated monthly payments. Its fixed-payment total assumes 28 payments of $250; a real account’s final payment can differ.

Assumptions

• The APR remains fixed throughout the estimated payoff period.
• A payment is made once per month, after that month’s interest accrues.
• Interest compounds monthly using APR ÷ 12.
• No new purchases, cash advances, balance transfers, fees, penalty pricing, or other account activity is included.
• The estimate excludes issuer-specific daily balance methods, billing-cycle dates, minimum-payment rules, and changes to payment amount.

How to Read a Credit Card Payoff Schedule

A schedule is a month-by-month estimate: it typically shows the opening balance, interest added, payment, and closing balance. In a fixed-payment model, interest is calculated on the balance before that month’s payment, so the first month’s interest at the example APR is about $83.33 ($5,000 × 0.0166667). A $250 payment would then reduce the balance by roughly $166.67 before later interest calculations.

The calculator summarizes the schedule as months, total paid, and estimated interest rather than displaying every row. A more detailed schedule can be built by repeating these steps: multiply the current balance by the monthly rate to estimate interest, add that interest to the balance, subtract the payment, and continue. If a payment is larger than the amount owed, the real last payment is capped at the amount due.

Use a current statement balance and the APR that applies to that balance. Cards may have different rates for purchases, cash advances, or transferred balances. If several rates apply, calculating each portion separately—or using the issuer’s payoff information—is more representative than treating everything as one balance at one APR.

Choosing Inputs and Understanding Limits

The planned payment should be an amount you are using as a scenario, not a promise about what the issuer will require. The calculator requires a positive payment and computes a finite payoff estimate only when the payment exceeds the first month’s interest. If the payment is equal to or below that interest, the balance does not decline under this fixed-rate model, so there is no finite payoff time to report. A zero or promotional APR also needs separate handling because this formula divides by the monthly rate.

• Balance: Use the amount currently owed for the rate being modelled, rather than a credit limit.
• APR: Enter the annual percentage rate as a percent, not a decimal. For example, enter 20 for 20%, not 0.20.
• Payment: Enter a monthly dollar amount. If it changes over time, this single-payment model cannot reproduce that pattern.

Rounding matters. The payoff formula estimates whole months, and interest in an actual account may be calculated daily and rounded on statements. Payment dates, new transactions, and fees can alter the result. A schedule is consequently most useful for understanding how payment size and APR affect a simplified payoff path, not for reconciling an account to the cent.

Common Payoff Schedule Questions

Does this calculator show my card’s exact payoff date?
No. It estimates whole monthly periods from a fixed APR and payment. Billing-cycle timing, daily interest, transactions, fees, and issuer rules can change both the date and final amount. Ask the issuer for a payoff amount tied to a specific date when exact figures are needed.

Why does my card statement show a different payoff estimate?
Its estimate may use a different balance, minimum-payment formula, interest calculation, payment date, or assumptions about future activity. Compare the inputs and method before treating two estimates as inconsistent.

What happens if my payment only covers the interest?
Under this model, the balance will not decrease if the payment is no greater than the interest added for the month. The formula has no finite payoff result in that case. A changing APR or balance can make the outcome different from the simplified estimate.

Can I include new purchases or fees?
Not as separate inputs here. They add to the balance and may have a different APR or timing. For an approximate scenario, a reader can adjust the starting balance, but that cannot reproduce the way separate transactions are billed.

Why is total paid calculated as payment times months?
That is the stated fixed-payment assumption used to make the estimate simple. In a real payoff, the final payment is generally limited to the remaining principal and accrued interest, so the actual total may be lower than this rounded-month illustration.

This result is an estimate for educational arithmetic, and the card issuer’s disclosure gives the exact figures.

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in bal | Credit card balance | $ | 5000 | 0.01 | 100000000
in apr | Interest rate (APR) | % | 20 | 0.01 | 100
in pmt | Planned monthly payment | $ | 250 | 0.01 | 100000000
out mon | Estimated months to payoff | months | ceil(round(-ln(1 - (apr / 1200) * bal / pmt) / ln(1 + apr / 1200), 6)) | 0
out tot | Estimated total paid | $ | pmt * mon | 2
out int | Estimated total interest | $ | pmt * mon - bal | 2