Illustrative example \u2014 read this first. The balance and the APR on this page are an illustrative example \u2014 use your own statement figure for both. Nothing here is a statistic or a recommendation for your household. Educational information only, not financial advice.
The example, and the model we use
The balance is $4,800. The rate is an illustrative APR of 24%, which is 24% \u00f7 12 = 2% per month \u2014 again, an illustrative example; use your own statement figure, because your card's real APR decides your real numbers. To keep the maths fully checkable, this example uses fixed monthly payments, stated plainly: Path A pays a fixed $150 a month, standing in for a minimum-style payment on this balance, and Path B pays a fixed $350 a month \u2014 the same $150 plus the extra $200. Real minimum payments are set by each issuer's own formula and shrink as the balance falls, which stretches a minimum-only path out even longer than Path A below; the fixed-payment version is used here so every figure on the page can be verified with the formula shown. No new spending is added to the card in either path.
Month by month: where the two paths separate
In month one, both paths are charged the same interest: $4,800 \u00d7 2% = $96. The difference is what is left for the balance itself. Path A's $150 payment clears $150 \u2212 $96 = $54 of principal, leaving $4,746. Path B's $350 clears $350 \u2212 $96 = $254 of principal, leaving $4,546. That gap then compounds in your favour: a lower balance is charged less interest the next month, so more of every later payment reaches principal. Watch the balances diverge:
| Month | Path A balance ($150/mo) | Path B balance ($350/mo) |
|---|---|---|
| Start | $4,800.00 | $4,800.00 |
| 1 | $4,746.00 | $4,546.00 |
| 6 | $4,459.36 | $3,197.74 |
| 12 | $4,075.75 | $1,393.33 |
| 17 | $3,719.35 | $0 \u2014 paid off |
| 52 | $0 \u2014 paid off | \u2014 |
By month 12 the extra $200 has already opened a $4,075.75 \u2212 $1,393.33 = $2,682.42 gap between the two balances. Path B makes its final, smaller payment of $66.93 in month 17 and is done. Path A is still carrying $3,719.35 at that point and does not finish until a final payment of $89.11 in month 52.
The totals, and how to check them
| Path A: $150/mo | Path B: $150 + $200 = $350/mo | |
|---|---|---|
| Months to pay off | 52 | 17 |
| Total interest paid | $2,939.11 | $866.93 |
| Total paid (balance + interest) | $7,739.11 | $5,666.93 |
The extra $200 a month makes this household debt-free 35 months sooner (52 \u2212 17) and saves $2,939.11 \u2212 $866.93 = $2,072.18 in interest. You can check the payoff times yourself with the standard amortisation formula, n = \u2212ln(1 \u2212 r \u00d7 PV \u00f7 PMT) \u00f7 ln(1 + r), where r = 0.02 and PV = $4,800. For Path A: \u2212ln(1 \u2212 96 \u00f7 150) \u00f7 ln(1.02) = \u2212ln(0.36) \u00f7 ln(1.02) \u2248 51.6, so 52 payments, the last one partial. For Path B: \u2212ln(1 \u2212 96 \u00f7 350) \u00f7 ln(1.02) \u2248 16.2, so 17 payments, the last one partial. The interest totals above come from running that same month-by-month calculation to the final payment \u2014 try it with your own balance and your own statement APR and the method transfers exactly.
Who benefits most from the extra $200?
The extra payment does the most work where the APR is highest, because every dollar of principal removed stops being charged that rate every month that follows. That is why the usual ordering is to send extra payments to the highest-APR balance first \u2014 the avalanche approach we compare with the snowball method in debt avalanche vs snowball. Two practical corollaries. First, the same $200 aimed at a low-rate balance saves far less interest than it does here at an illustrative 24% APR, so order matters as much as amount. Second, a falling balance also lowers the share of your credit limits in use, which is the mechanism in our credit utilisation worked example. If you are weighing this extra payment against building savings first, work through emergency fund or pay off debt? before deciding \u2014 and for the wider payoff picture, see our main guide to paying off credit card debt.
Finding the $200: two worked cuts
The extra $200 has to come from somewhere real. Two illustrative line-by-line cuts show the scale of change involved \u2014 your own lines will differ, but the arithmetic habit is the point. Cut one: eating out falls from $240 a month to $140 a month, freeing $240 \u2212 $140 = $100. Cut two: a grocery plan trims the monthly shop from $520 to $460, freeing $60, and cancelling $40 of unused subscriptions and apps frees the remaining $40. Total: $100 + $60 + $40 = $200. Funding extra payments from small monthly set-asides like these is the same habit as a sinking fund run in reverse \u2014 a named line, funded on payday, for a named job.
Frequently asked questions
How much interest does an extra $200 a month save?
In this worked example \u2014 a $4,800 balance at an illustrative 24% APR, fixed payments \u2014 paying $350 instead of $150 a month cuts total interest from $2,939.11 to $866.93, a saving of $2,072.18, and shortens the payoff from 52 months to 17. Your saving depends on your own balance and statement APR.
Why does this example use fixed payments instead of minimum payments?
Because real minimums are set by each issuer's own formula and shrink as the balance falls, which makes the maths hard to verify on the page. Fixed payments of $150 and $350 keep every figure checkable with the amortisation formula shown; a shrinking minimum would stretch the minimum-only path out even longer.
Should the extra $200 go to my highest-rate card?
Mathematically, extra payments save the most interest on the highest-APR balance, because each dollar removed stops being charged that rate. That ordering is the avalanche method; our avalanche vs snowball guide compares it with paying smallest balances first for motivation.
This guide is educational information, not financial advice. For advice about your specific situation, consider speaking with a qualified financial professional. See our Disclaimer.