Credit Card Calculator — Payoff Time & Total Interest
See exactly how long it takes to clear a credit card balance and how much interest you pay in total — enter your balance, APR and fixed monthly payment.
%
Time to clear the balance at this fixed monthly payment
6,522.1
total paidPrincipal
76.7%
Total interest
23.3%
- 1
Monthly rate
r = 20% ÷ 12 ÷ 100 = 0.016667 - 2
Monthly interest ÷ payment
5,000 × 0.016667 ÷ 200 = 0.416667If this ratio reaches 1 the balance never decreases. - 3
Months (exact)
−ln(1 − 0.416667) ÷ ln(1 + 0.016667) = 32.61 - 4
Months to pay off (rounded up)
⌈32.61⌉ = 33
How does this calculator work?
A credit card balance P at APR r (monthly rate r/12) pays off in n = −log(1−P·r/M)/log(1+r) months at fixed payment M. Total interest = total paid minus the original balance. Paying more per month cuts both payoff time and total interest far more than proportionally.
Formula
How this is calculated
Every month a credit card issuer charges interest on the outstanding balance at a monthly rate of APR ÷ 12. If your payment M exceeds that month's interest, the surplus reduces the principal; otherwise the balance grows. The exact payoff formula is n = −log(1 − P·r/M) / log(1+r), derived from the standard annuity equation — the same math used for mortgages and car loans.
For the payment to make any progress, M must exceed the monthly interest P × r. At 20% APR on a $5,000 balance, that threshold is about $83/month — any payment below that amount means the balance grows despite paying every month. A $200 payment clears the same balance in about 35 months; bumping to $250 cuts it to 26 months and saves hundreds in interest.
The donut chart shows the total split between principal and interest, and the area curve traces the balance month by month, revealing the characteristic slow-then-fast paydown: early payments mostly cover interest, while later ones chop quickly through the small remaining principal.
Frequently asked questions
APR (Annual Percentage Rate) is the yearly interest rate charged on balances you carry. A 20% APR equals roughly 1.67% per month. Most US cards charge 18–30% APR; interest typically compounds daily but is billed monthly.
If your payment equals the interest that accrues that month, none of it reduces the principal — the balance is unchanged. Below that threshold the balance grows. The minimum payment needed to make any progress is balance × APR ÷ 12 ÷ 100.
Significantly. On a $5,000 balance at 20% APR, paying $200/month costs about $1,700 in interest over 35 months. Paying $250/month costs about $1,200 over 26 months — saving $500 and 9 months for just $50 more per month.
Also known as
TG we-Calculate Editorial Team. (2026). Credit Card Calculator — Payoff Time & Total Interest [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/credit-card-calculator
TG we-Calculate Editorial Team. "Credit Card Calculator — Payoff Time & Total Interest." TG we-Calculate. 2026. https://we-calculate.com/calculator/credit-card-calculator.
TG we-Calculate Editorial Team, "Credit Card Calculator — Payoff Time & Total Interest," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/credit-card-calculator
@misc{wecalculate_credit_card_calculator, title = {Credit Card Calculator — Payoff Time & Total Interest}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/credit-card-calculator}}, year = {2026}, note = {TG we-Calculate} }
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