How it works
Enter three figures — your current statement balance, the purchase APR your issuer charges, and the dollar amount you send each month — and the tool projects how many billing cycles remain until the account hits zero, plus the cumulative finance charges you'll rack up along the way.
This is the front-line reality check for anyone carrying revolving debt. The card issuer sets the annual percentage rate; you control only the payment size. The gap between sending the bare minimum versus a fixed, larger amount is where households quietly bleed thousands in interest year after year.
| Scenario | What the tool reveals |
|---|---|
| Minimum-only | Timeline stretches decades; interest often exceeds the original purchase total |
| Fixed payment above minimum | Timeline collapses; finance charges drop sharply |
| Aggressive fixed payment | Account cleared in months; interest becomes negligible |
The formula
n = −ln(1 + B × r / P) / ln(1 + r)
B is the outstanding balance, r is the monthly periodic rate (APR ÷ 12), and P is the fixed monthly payment. Total interest equals (P × n) − B.
Worked example
Consider a $4,500 revolving balance at 22.99% APR. The statement lists a minimum payment of roughly $135 — about 3% of what you owe. Here's what unfolds if you mail only that amount and the issuer keeps recalculating the floor each cycle as the balance shrinks.
Monthly periodic rate: 22.99% ÷ 12 = 1.9158%
First month interest: $4,500 × 0.019158 = $86.21
Of that $135 remittance, only about $48.79 touches the principal. The rest covers finance charges. Next cycle the balance is slightly lower, the minimum drops a little, and the pattern repeats.
Principal reduction, month 1: $135 − $86.21 = $48.79
Because the minimum is pegged to a percentage of what you owe, it keeps shrinking alongside the balance. You're effectively treading water — the issuer designs it that way. Running the amortization to its conclusion:
Total cycles to reach zero: ≈ 250 months (roughly 21 years)
Total amount sent: $135 avg × 250 months ≈ $33,750
Total interest charged: $33,750 − $4,500 = $29,250
You would hand the bank nearly $29,250 in finance charges on a $4,500 purchase — more than six times the original debt — and carry the account for over two decades. That is the minimum-payment trap in cold arithmetic.
Now hold the payment flat at $200 instead of letting it shrink:
Fixed payoff time at $200/mo: ≈ 31 months
Total interest at $200/mo: ($200 × 31) − $4,500 = $1,700
Same balance, same APR. Locking the remittance at $200 cuts the timeline from 21 years to under three and drops the interest burden from $29,250 to $1,700.
Things to watch
Card issuers frequently apply a small floor — often $25 or $35 — when the percentage-based minimum dips below it. That floor shortens the tail end of the timeline somewhat, but the first decade of a minimum-only scenario still burns far more in finance charges than most people expect.
Variable APRs also shift when the Federal Reserve adjusts its benchmark rate. A balance projected at 22.99% today could climb higher mid-repayment, extending the schedule. And if you continue swiping the card for new purchases while carrying a balance, grace periods vanish — every new charge starts accruing interest immediately, on top of the existing revolving balance.
This projection is an estimate for planning purposes, not professional financial advice. Actual statements may differ due to fees, rate changes, or issuer-specific minimum calculations.