Pay Off a Balance Transfer: Calculator and Guide

This calculator estimates how many months it will take to pay off a balance-transfer credit card balance when you enter the amount transferred, its annual percentage rate (APR), and your monthly payment. It returns the estimated payoff time and the total paid using that fixed payment; it does not model a promotional rate ending or fees.

Formula

The calculator estimates the number of whole monthly payments needed to repay a fixed balance at a fixed monthly interest rate. The underlying payment-time formula is:

n = -ln(1 - rP / M) / ln(1 + r)

The displayed payoff time is ceil(round(n, 6)), meaning the estimated fractional result is rounded to six decimal places and then rounded up to a whole month. The monthly rate is r = APR / 1200, converting the annual percentage rate to a monthly decimal rate. Variables are:

• P: transferred balance, in dollars.
• APR: annual percentage rate, entered as a percentage.
• r: monthly interest rate, as a decimal.
• M: monthly payment, in dollars.
• n: calculated payoff time, in months.

Total paid is estimated as M × months. Because payments occur in whole months, this total treats every payment as the same amount, including the last one. In reality, a final payment is often smaller than the regular payment; the estimate is therefore a simple comparison tool, not a card statement payoff quote.

Worked Example

Using the default inputs—$5,000 transferred, 18% APR, and a $250 monthly payment:

1. Convert the APR to a monthly decimal rate: r = 18 / 1200 = 0.015, or 1.5% per month.
2. Calculate the ratio in the logarithm: 1 - (r × P / M) = 1 - (0.015 × 5000 / 250) = 0.7.
3. Calculate the unrounded payment time: -ln(0.7) / ln(1.015) ≈ 23.97 months.
4. Round up to a whole month: ceil(23.97) = 24 months.
5. Multiply the regular payment by the estimated months: $250 × 24 = $6,000 total paid.

The calculator outputs 24 months and $6,000. The real final payment may be lower than $250, so the actual total can differ.

Assumptions

• The APR and monthly payment stay fixed throughout repayment.
• Payments are made once per month; the model treats the monthly rate as APR divided by 12.
• Interest compounds monthly for the estimate. Card issuers may calculate interest using daily balances and payment dates, so statement figures can differ.
• Balance-transfer fees, annual fees, new purchases, late payments, taxes, and changes in card terms are not included.

What Paying Off a Balance Transfer Means

A balance transfer moves some or all of a credit-card balance to another card, usually under terms that may include a promotional interest period. The transfer does not erase the debt: the amount transferred, any applicable fee, and interest charged under the receiving card’s terms still have to be repaid. The calculator estimates repayment under one steady APR, so it is most useful when that is a reasonable simplification of the terms that apply.

Check the card agreement or account disclosure for the promotional APR, how long it applies, the rate after the promotion, the balance-transfer fee, and payment requirements. These are inputs to the real cost but are not supplied by this calculator. Do not assume that a promotional rate applies to purchases, cash advances, or every transferred balance; terms can differ by transaction type.

How to Use the Payoff Estimate

Enter the amount actually transferred, the APR that applies to that balance, and a fixed monthly payment you want to examine. If a transfer fee is added to the card balance, include it in the balance input for a closer estimate. If the APR changes during repayment, a single-rate result will not represent the full schedule.

• Use the APR as a percentage, such as 18 for 18%, not 0.18.
• Use the payment amount that goes toward the card each month, not a minimum payment that may change as the balance falls.
• Run separate estimates for different payment amounts to see how the assumed schedule changes.
• Compare the estimated months with the time remaining in any promotional period, while accounting for the card’s actual terms.

The result is an arithmetic estimate, not a statement of what a card issuer will charge or a recommendation about transferring a balance. For a precise payoff amount, use the account’s current balance and payment information and confirm details with the issuer.

Promotional Rates, Fees, and Common Problems

A promotional APR can make the transfer-period estimate very different from the eventual repayment cost. If the promotion ends before the balance is cleared, the remaining amount may be subject to a different APR under the agreement. This fixed-rate calculator cannot calculate that transition. A more detailed schedule would need the promotion’s duration, the later APR, payment timing, and the applicable interest method.

A transfer fee increases the amount owed. For example, if a fee is charged and added to the balance, calculating from the original debt alone understates the amount to repay. Enter the full resulting balance when it is known. Also avoid treating a transfer as completed before it appears in the receiving account: balances, payment due dates, and interest on the old account may continue to matter while processing is underway.

The formula requires a payment large enough to cover the month’s interest. With a positive APR, if the payment is no greater than the starting month’s interest, the balance will not decline under this model; the logarithm is undefined for that input. A calculator may show an invalid or unavailable result rather than a payoff month. A payment barely above interest can produce a very long estimate, and changes in rates, fees, or payment behavior can alter it substantially.

Frequently Asked Questions

Should I pay off a balance transfer before the promotional period ends?
That depends on the terms and your circumstances; this calculator cannot make that decision. Compare the estimated payoff time with the promotion’s end date, and check what APR and fees apply afterward in the card disclosure.

Does a balance transfer pay off my old card?
A completed transfer pays the transferred amount to the old account, but it may not cover the entire old balance. Confirm that the transfer posted and continue making required payments on each account until its balance and due-date obligations are clear.

Does the calculator include a balance-transfer fee?
No. Add a fee to the balance input if it is charged to the receiving card and you know the resulting total. Fees and how they are applied depend on the card’s terms.

Why is the payoff time unavailable for my payment?
The assumed payment may not exceed the interest charged in the first month. At that payment level, this formula cannot calculate a declining balance that reaches zero. Check the APR, payment, and balance entries.

Will paying the same amount each month make the final payment exactly that amount?
Not usually. The calculator multiplies the monthly payment by the rounded-up number of months for a simple total. A real payoff schedule commonly ends with a smaller final payment, and daily interest or fees can change the amount.

This result is an estimate for educational purposes, and the card issuer’s disclosure and account figures provide the applicable terms and exact amounts.

Related

• Credit Card Balance Transfer Payoff Calculator
• Balance Transfer Zero Percent Balance Calculator
• 0% APR Balance Transfer Calculator and Costs

in bal | Balance transferred | $ | 5000 | 0.01 | 100000000
in apr | Interest rate (APR) | % | 18 | 0.01 | 100
in pmt | Monthly payment | $ | 250 | 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 tot | Total paid | $ | pmt * mos | 2