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Formula
Months n = −ln(1 − r × B ÷ P) ÷ ln(1 + r), rounded up; Payment for n months P = B × r(1 + r)^n ÷ ((1 + r)^n − 1)
- B
- the current card balance
- P
- the fixed monthly payment
- r
- the monthly rate, the APR ÷ 12 as a decimal (24% → 0.02)
- n
- the number of monthly payments; the last one is smaller and only clears what is left
Two questions this calculator answers
The credit card payoff calculator has two modes:
- Fixed monthly payment. You know how much you can put toward the card each month. The calculator tells you how many months it will take to reach zero, the total interest, the total you will pay and the size of the final, smaller payment.
- Payoff by a target. You know when you want to be debt-free. Enter the number of months and the calculator gives the monthly payment you need, plus the interest you will pay along the way.
Both modes show a yearly schedule of how much of your payments went to the balance and how much to interest, and the balance left at the end of each year.
How to calculate credit card payoff time by hand
Say you owe $2,500 at 18% APR and pay $125 a month.
- Monthly rate: r = 0.18 ÷ 12 = 0.015.
- First month’s interest: $2,500 × 0.015 = $37.50, so $87.50 of the first payment reduces the balance.
- Months to pay off: n = −ln(1 − 0.015 × 2,500 ÷ 125) ÷ ln(1.015) = −ln(0.7) ÷ ln(1.015) ≈ 0.3567 ÷ 0.0149 ≈ 23.96.
- Round up: 24 payments, the last one slightly smaller than $125.
- Total interest: about $494.57.
The formula only works when the payment is larger than r × B. If it is not, the logarithm has no answer, which is the maths saying the balance will never fall. The calculator checks this first and tells you the payment you need to beat.
How long it takes at different payments
A $4,000 balance at 21% APR, with no new charges:
| Monthly payment | Months to pay off | Total interest |
|---|---|---|
| $100 | 70 | $2,940.08 |
| $150 | 37 | $1,435.32 |
| $200 | 25 | $966.43 |
| $300 | 16 | $595.21 |
Going from $100 to $150 a month cuts almost three years and more than $1,500 of interest. The first month’s interest at 21% is $70, so at $100 only about $30 of each early payment reduces the debt; at $150 it is about $80.
The payment needed for a payoff date
The same $4,000 at 21% APR, cleared in a set number of months:
| Pay off in | Monthly payment | Total interest |
|---|---|---|
| 12 months | $372.46 | $469.46 |
| 24 months | $205.54 | $933.02 |
| 36 months | $150.70 | $1,425.21 |
| 48 months | $123.86 | $1,945.41 |
This is the same formula used for an installment loan, which is why a fixed-payment plan is sometimes compared with a personal loan or balance transfer. If you move the debt to a loan, compare the loan’s APR and fees with this table using the loan calculator.
How much the APR matters
Paying $150 a month on $4,000:
| APR | Months to pay off | Total interest |
|---|---|---|
| 15% | 33 | $896.14 |
| 20% | 36 | $1,334.35 |
| 25% | 40 | $1,899.65 |
| 29% | 44 | $2,496.02 |
Card APRs are high compared with most loans. The Federal Reserve’s G.19 release reported an average of about 22% on accounts assessed interest at commercial banks in August 2026. A lower rate, whether negotiated or through a balance transfer, shortens the payoff even at the same payment, but check transfer fees and when any promotional rate ends.
How card interest really works
The CFPB explains that most issuers calculate interest daily: the APR is converted to a daily periodic rate and applied to your average daily balance over the billing cycle. If you pay your full statement balance by the due date, a grace period usually means no interest on purchases. This calculator simplifies that to APR ÷ 12 on the balance each month, which gives a close estimate for planning. Your statement’s minimum payment warning shows how long minimum payments alone would take, and comparing it with the result here shows what a fixed payment saves.
Common mistakes
- Still using the card. New purchases add to the balance and push the payoff date back. The results assume the card is not used.
- Paying just above the interest. It technically reduces the balance, but very slowly. A payment of $5 more than the monthly interest can take over a decade.
- Forgetting a promotional rate expires. If a 0% offer ends, the remaining balance starts accruing interest at the regular APR.
- Spreading extra money across every card. Extra payments usually save the most when aimed at the highest APR.
Glossary
- APR. The annual percentage rate on the card, the yearly cost of carrying a balance.
- Daily periodic rate. The APR divided by the number of days in the year, applied to each day’s balance.
- Grace period. The time between the end of a billing cycle and the due date in which paying in full avoids interest on purchases.
- Minimum payment. The smallest amount the issuer accepts each month, often a percentage of the balance plus interest.
Worked examples
A fixed $250 a month
A $7,400 balance at 23.99% APR, paying $250 every month with no new charges.
Inputs (Fixed monthly payment): Card balance = $7400; APR = 23.99 %; Monthly payment = $250
Monthly rate = 23.99% ÷ 12; first month’s interest = $7,400.00 × monthly rate = $147.94 $250.00 − $147.94 = $102.06 goes to the balance in month 1 Repeating each month: 45 payments of $250.00 + a final $65.31
Answer: Paying $250.00 a month on $7,400.00 at 23.99% APR clears the card in 46 months with $3,915.31 of interest.
Debt-free in two years
Clearing a $3,850 balance at 19.5% APR in 24 months.
Inputs (Payoff by a target): Card balance = $3850; APR = 19.5 %; Pay off in = 24 months
r = 19.5% ÷ 12; n = 24 Payment = $3,850.00 × r(1 + r)^24 ÷ ((1 + r)^24 − 1) = $195.01
Answer: To pay off $3,850.00 at 19.5% APR in 24 months, pay $195.01 a month ($830.23 total interest).
A payment that barely beats the interest
A $5,000 balance at 27.5% APR with $120 a month, only about $5 above the first month’s interest of $114.58.
Inputs (Fixed monthly payment): Card balance = $5000; APR = 27.5 %; Monthly payment = $120
Monthly rate = 27.5% ÷ 12; first month’s interest = $5,000.00 × monthly rate = $114.58 $120.00 − $114.58 = $5.42 goes to the balance in month 1 Repeating each month: 136 payments of $120.00 + a final $87.76
Answer: Paying $120.00 a month on $5,000.00 at 27.5% APR clears the card in 137 months with $11,407.76 of interest.
Assumptions and limitations
- You make no new purchases, cash advances or balance transfers while paying the card off, and no fees or penalty rates are added.
- Interest is estimated monthly at APR ÷ 12 on the balance. Most issuers actually charge a daily periodic rate on the average daily balance, so real interest can differ slightly from month to month.
- The APR stays the same for the whole payoff. Promotional rates that end, or variable rates that change with the prime rate, are not modeled.
- The payment is the same every month (not a minimum payment that shrinks as the balance falls), and it must be larger than the first month's interest. The last payment only clears the remaining balance.
- Payoffs longer than 50 years (600 months) are not shown.
Frequently asked questions
How long will it take to pay off my credit card?
Enter your balance, APR and the amount you will pay each month in Fixed monthly payment mode. The calculator steps through each month, adding interest and subtracting your payment, until the balance reaches zero. A $4,000 balance at 21% APR takes 37 months at $150 a month and 25 months at $200.
How do I calculate credit card payoff with interest?
Divide the APR by 12 to get the monthly rate r, then use n = −ln(1 − r × B ÷ P) ÷ ln(1 + r) and round up. For $2,500 at 18% with $125 payments, r = 0.015 and n ≈ 23.96, so it takes 24 months. Total interest is everything you pay minus the starting balance.
Why does the calculator say my payment is too low?
If your payment is not more than the interest charged in a month, the balance never goes down. At 24% APR a $5,000 balance is charged about $100 of interest a month, so a $100 payment only covers interest. The calculator tells you the minimum amount above that line.
How much should I pay to be debt-free in 3 years?
Switch to Payoff by a target and enter 36 months. For $4,000 at 21% APR, the payment is $150.70 a month, with $1,425.21 of interest in total. Paying it off in 24 months instead takes $205.54 a month and cuts the interest to $933.02.
Is paying only the minimum a problem?
Minimum payments are usually a small percentage of the balance, so they shrink as the balance falls and the payoff can stretch over many years. Your statement shows how long minimum payments would take. Paying a fixed amount above the minimum, as this calculator assumes, shortens the payoff a lot.
Why is my card's interest a bit different from the estimate?
Card issuers usually apply a daily periodic rate to your average daily balance, and the number of days in each billing cycle varies. The calculator uses APR ÷ 12 each month, which gives a close estimate but will not match your statement to the cent.
Does it handle several cards?
Not in one run. To compare cards, run each one separately. Paying extra on the card with the highest APR first while making the required payments on the others usually minimizes total interest.
Sources
- How does my credit card company calculate the amount of interest I owe? — Consumer Financial Protection Bureau. Checked October 10, 2026.
- What is a credit card interest rate? What does APR mean? — Consumer Financial Protection Bureau. Checked October 10, 2026.
- Consumer Credit – G.19 (interest rates on credit card plans) — Board of Governors of the Federal Reserve System. Checked October 10, 2026.