Credit Card Payoff Plan Calculator and How It Works

A credit card payoff plan estimates how many months it will take to clear a balance when you make a fixed monthly payment, and how much interest you will pay along the way. Enter your balance, APR, and planned monthly payment to see an estimated payoff time and total interest; the calculation assumes no new purchases or fees.

Formula

The calculator finds the number of whole monthly payments needed for a fixed payment to reduce the balance to zero, then estimates interest as all payments minus the starting balance.

• Monthly interest rate, r: APR ÷ 1,200, expressed as a decimal rate per month.
• Months, n: round up [−ln(1 − r × B ÷ M) ÷ ln(1 + r)]. Rounding up counts the final partial payoff month as a payment month.
• Estimated interest, I: M × n − B.
• B: starting balance in dollars; APR: annual percentage rate in percent; M: fixed monthly payment in dollars.

The logarithm formula assumes the same payment is made at the end of each month and the balance accrues interest monthly. It treats the last payment as equal to the others, so its total-interest result is a planning estimate; in practice, the final payment may be smaller. The calculator does not model a separate minimum-payment rule or payment allocation across multiple balances.

Worked Example

Using the default inputs: balance B = $5,000, APR = 20%, and payment M = $200 per month.

1. Convert APR to a monthly rate: r = 20 ÷ 1,200 = 0.0166667, or about 1.66667% per month.
2. Apply the payoff-month formula: n = ceil[−ln(1 − 0.0166667 × 5,000 ÷ 200) ÷ ln(1.0166667)] = ceil(34.94) = 35 months.
3. Estimate interest using the displayed fixed-payment method: $200 × 35 − $5,000 = $2,000.

The result is 35 months and $2,000 in estimated interest. Actual interest and the final payment can differ because issuers commonly calculate interest using account activity and billing-cycle details rather than this simplified fixed-payment model.

Assumptions

• The APR and monthly payment remain fixed throughout the estimate.
• Payments are made once per month at the end of each period.
• Interest compounds monthly using APR ÷ 12.
• No new purchases, late payments, payment fees, annual fees, promotional-rate changes, or other charges are included.

How to Build a Practical Payoff Plan

The calculator answers a narrow question: what happens if a specific balance, rate, and payment stay unchanged? To turn that estimate into a plan, first use the current account balance and APR shown on a recent statement, then choose a monthly amount that fits your budget without assuming future income or rates. Compare the estimated payment period with your own target and revise the payment input to see how the result changes.

• List every card separately, including its balance, APR, minimum due, and due date. A single-card result does not represent a multi-card payoff strategy.
• Account for essential bills and irregular costs when deciding what payment amount to test. The calculator cannot judge whether a payment is manageable.
• Keep making at least the required payment shown by the card issuer. The model’s fixed amount is not a substitute for the issuer’s minimum-payment calculation.
• Update the calculation when balances, APRs, or monthly payment amounts change. A new purchase or fee changes the amount to repay.

For multiple cards, a common budgeting approach is to direct extra repayment to one balance while continuing required payments on others. Paying the highest-rate balance first can reduce interest in a simplified comparison if rates, balances, and payments stay as assumed; paying the smallest balance first can produce a quicker account payoff milestone. Neither comparison is calculated here, and changing rates or fees can change the arithmetic.

What the Estimate Leaves Out

Credit card interest may be calculated from daily balances and the number of days in a billing period. The exact amount can therefore differ from a monthly-compounding estimate, especially when payments arrive on different dates, the APR changes, or purchases and credits post during a cycle. The card agreement and statement explain the issuer’s calculation method and account-specific terms.

Also, a fixed payment may not remain above the amount of interest accruing. In that situation, the balance will not decline as modeled. The formula’s logarithm is undefined when the payment is less than or equal to the first month’s estimated interest (M ≤ r × B); the calculator may show an error rather than a payoff estimate. Even when the payment is slightly above that amount, small changes in APR or new charges can greatly extend the payoff time.

The interest output uses the rounded-up month count multiplied by the full monthly payment. That convention is useful for a clear, conservative planning estimate, but it can overstate the actual total because a real final payment may only cover the remaining balance and interest. Do not interpret the result as an issuer payoff quote or an exact statement of future charges.

Ways to Compare Changes

Change one input at a time to understand what drives the result. For example, hold the $5,000 balance and 20% APR constant while testing different payment amounts; then return to the original payment and test a different APR. This separates the effect of repayment pace from the effect of interest. Use the APR that applies to the balance being modeled; a card can have different rates for different transaction categories or promotional balances.

Options such as a balance transfer, consolidation, or a lower-rate arrangement involve terms, fees, and eligibility details that this calculator does not evaluate. To compare any alternative, use its actual quoted rate, fees, repayment schedule, and any conditions supplied by the provider, and account for whether the payment or rate can change. The arithmetic here is not a recommendation to open, close, transfer, or borrow through an account.

Frequently Asked Questions

How much should I pay on my credit card each month?
That depends on your budget, account terms, and payoff timeline. This calculator lets you test a payment amount, but it does not determine what is affordable or replace the minimum payment stated by the issuer.

Does a higher monthly payment reduce interest?
With the same balance and APR, a larger payment generally reduces the balance faster and leaves less time for interest to accrue. The estimate assumes the payment is made consistently and no new charges are added.

Why does my statement show a different payoff amount?
The model uses monthly compounding and a fixed payment. A statement or payoff figure can reflect daily balance calculations, payment dates, billing-cycle length, new transactions, fees, or an APR change.

Can I use this for several credit cards?
Not as one combined calculation if the cards have different APRs or payment terms. Calculate each balance separately for an individual estimate, and remember that payments to one card do not satisfy another card’s required payment.

What if my payment is less than the interest?
The balance will not be paid off under the assumptions in this formula; it may stay level or increase. Review the rate, payment, new charges, and account terms rather than treating an undefined result as a payoff date.

This result is an estimate for education, and your card issuer’s disclosures and account terms provide the exact figures.

Related

• Amortization Schedule Using Payment Amount
• Amortization Schedule Spreadsheet: Payment and Interest
• Amortization Schedule by Month: Payment and Interest

in bal | Credit card balance | $ | 5000 | 0.01 | 100000000
in apr | Interest rate (APR) | % | 20 | 0.01 | 100
in pmt | Planned monthly payment | $ | 200 | 0.01 | 100000000
out mos | Months to pay off | months | ceil(round(-ln(1 - (apr / 1200) * bal / pmt) / ln(1 + apr / 1200), 6)) | 0
out int | Estimated total interest | $ | pmt * mos - bal | 2