Paying only the minimum on a $4,100 card: 202 months and $5,394 of interest

Same debt as the earlier examples: $4,100 on a card at 18.9% APR, no new charges. Paid at $200 a month, that takes 25 months and $890 of interest, $4,990 total. At $130 a month it takes 44 months and $1,612 of interest.

Now pay only the minimum. Most issuers set the minimum at that month's interest plus 1% of the balance, with a $25 floor. On $4,100 that first minimum is $105.58 — and it shrinks every month as the balance falls. That is the trap: the payment falls with the balance, so the balance barely falls at all.

What minimum-only actually does

Month 12: balance $3,627. You have paid $733 of interest and only $473 of principal. After a full year, the balance is still 88% of where it started.
Month 60: balance $2,222, interest paid so far $2,912. Five years in, you have paid more in interest than half the original debt, and the balance is still over half.
Month 71: the balance finally halves to $2,000 — nearly six years in.
Month 120: balance $1,204, interest paid $4,490. Ten years in, interest paid already exceeds the original $4,100 balance.
Month 202: done. 16 years and 10 months, $5,394 of interest, $9,494 total paid on a $4,100 purchase.

The minimum is not a payoff plan. It is a plan for the balance to outlive the thing you bought with it.

Adding a fixed $50 or $100 changes everything

The minimum falls because it is a percentage of a shrinking balance. Add a fixed amount on top and the payment stops shrinking — the extra goes straight at principal every month.

Minimum + $50: 57 months, $1,741 of interest, $5,841 total. That saves $3,653 and 145 months against minimum-only. The balance halves in month 26 instead of month 71, and drops below $1,000 in month 42 instead of 139.
Minimum + $100: 34 months, $1,066 of interest, $5,166 total. That saves $4,328 and 168 months. The balance halves in month 16 and drops below $1,000 in month 25.
For comparison, a fixed $200 a month (no minimum formula at all): 25 months, $890 of interest.

The jump from minimum-only to minimum + $50 is the biggest single improvement in this whole series: $3,653 saved for $50 a month. The jump from +$50 to +$100 saves another $675. The jump from +$100 to a fixed $200 saves another $176. The first $50 does most of the work because it breaks the shrinking-payment loop.

Why the minimum feels affordable and isn't

The first minimum, $105.58, is lower than the $130 and $200 fixed payments in the earlier articles, so it feels like the easy option. It is the most expensive option in the series by a wide margin: $5,394 of interest against $890 at $200 a month — six times as much, for the same $4,100.

The mechanism is the declining payment. At $200 fixed, the payment stays $200 while the interest portion shrinks, so more and more of each payment hits principal. Under the minimum formula the payment shrinks with the balance, so the principal portion stays small — in year one it averages under $40 a month. The card is designed so that paying the minimum keeps you paying.

The honest notes

Minimum formulas vary by issuer — some use 1% plus interest, some use 2% of the balance, some use a flat percentage with a different floor. A 2%-of-balance minimum on this same debt takes 359 months and $11,058 of interest, which is worse still. The shape is the same under any of them: a percentage-of-balance minimum falls as the balance falls, and the payoff stretches into decades. Check your own statement for the exact formula.
The calculator linked below runs a fixed monthly payment directly — balance, APR, payment. For a minimum-only run, the payment changes every month, so the calculator cannot do it in one pass; the numbers here come from the same month-by-month model, simulated with the interest-plus-1% formula and a $25 floor.
This comparison assumes no new charges and every payment on time. A missed payment can add a late fee and, on some cards, a penalty APR — both make the minimum-only path longer still.
This is arithmetic on one example, not advice.