How to use this calculator
- Enter the current balance from your latest statement.
- Enter your APR (annual percentage rate). It’s printed on your statement, usually near the interest charge.
- Enter what you plan to pay every month, then select Calculate.
The result shows the month of your last payment, the total interest, and a tip showing what paying $100 more each month would change.
How it’s calculated
Each month, interest is added to the balance and then your payment is subtracted. The calculator repeats this until the balance reaches zero. The number of months also follows this formula:
r = APR ÷ 12 ÷ 100
months = −ln(1 − r × balance ÷ payment) ÷ ln(1 + r)
months = −ln(1 − r × balance ÷ payment) ÷ ln(1 + r)
Worked example
A $6,500 balance at 22.99% APR with a $250 monthly payment:
r = 22.99 ÷ 1200 = 0.019158
First month’s interest = 6,500 × 0.019158 = $124.53
months = −ln(1 − 0.019158 × 6,500 ÷ 250) ÷ ln(1.019158) = 36.3
→ 37 payments (the last one is smaller)
Total paid = $9,082 Total interest = $2,582
First month’s interest = 6,500 × 0.019158 = $124.53
months = −ln(1 − 0.019158 × 6,500 ÷ 250) ÷ ln(1.019158) = 36.3
→ 37 payments (the last one is smaller)
Total paid = $9,082 Total interest = $2,582
Raising the payment to $350 clears the same card in 24 months and cuts the interest to $1,611 — 13 months sooner and $971 less.
Ways to pay it off faster
- Stop adding new purchases to the card while you pay it down.
- Ask your issuer for a lower APR. A good payment history makes this more likely.
- Consider a 0% balance transfer only if you can clear it before the promotional rate ends, and include the transfer fee in your maths.
- Set up automatic payments so you never pay a late fee.
