Extra Payment Calculator
An extra payment is any amount above the minimums, applied to one target debt while the rest keep their minimums. Because it goes entirely to principal, it removes balance that would otherwise be charged interest every month for the rest of the plan. The effect compounds: the first extra $50 a month saves more than the second, and both save far more than their face value.
This calculator takes your debts and current extra amount and shows what adding $50, $100, $250 or $500 a month does to your payoff date and total interest. On the example debts, going from $0 to $100 extra saves about $1,600 in interest and finishes more than a year sooner. Use it to decide whether a specific expense is worth cutting.
Results
An extra $100 a month
Saves $1,616 and 14 months
Your current plan finishes April 2030 with $4,172 in interest.
| Extra per month | Debt-free | Months | Total interest | Months saved | Interest saved |
|---|---|---|---|---|---|
| $0.00 (now) | Apr 2030 | 43 | $4,172 | 0 | $0.00 |
| $50.00 (+$50.00) | Aug 2029 | 35 | $3,176 | 8 | $996 |
| $100 (+$100) | Feb 2029 | 29 | $2,556 | 14 | $1,616 |
| $250 (+$250) | Apr 2028 | 19 | $1,602 | 24 | $2,569 |
| $500 (+$500) | Oct 2027 | 13 | $1,015 | 30 | $3,157 |
At minimum payments only, these debts take 4 years 10 months and cost $4,999 in interest. With $0.00 extra a month you are debt-free in 3 years 7 months after $4,172 in interest.
Enable JavaScript to edit the numbers above and see your own plan, charts, and month-by-month schedule.
Frequently asked questions
Which debt should the extra payment go to?
The highest APR, for the lowest total cost; that is the avalanche order the calculator uses by default. If you want the psychological boost of clearing a balance quickly, send it to the smallest balance instead. Either way, put the extra on one debt at a time rather than spreading it across all of them.
Is it better to pay extra monthly or in one lump sum?
Monthly is usually easier to sustain and starts saving interest immediately, but a lump sum applied early is worth more than the same amount spread over a year, because principal removed today stops accruing interest right away. If you have both options, do the lump now and keep the monthly extra going.
Why does the first $50 save more than the next $50?
Because interest saved depends on how much balance remains and for how long. The first extra payment shortens the plan the most and removes the most interest-bearing months. Each additional increment shortens an already shorter plan, so the marginal saving falls even though every dollar still helps.
Should I tell my lender to apply extra to principal?
For installment loans, yes: some servicers apply an overpayment to next month's payment instead of principal unless you specify. Credit cards apply anything above the minimum to the highest-rate balance by law. Check the payment screen or call, and confirm on the next statement that the balance dropped by the full amount.
How much extra do I need to pay off debt in a set number of years?
Add increments in the calculator until the debt-free date lands where you want it. For a quick estimate, divide your total balance by the number of months and add roughly half the first month's interest; then confirm with the schedule, which accounts for interest falling as balances shrink.