Run it on your own numbers
Debt Payoff by Extra Payment Calculator
Enter your balance, rate and payment to get a payoff date, interest saved per scenario, and the extra amount a target debt-free date would need.
Open the debt payoff by extra payment calculatorWhat an extra payment actually does
Interest each month is charged on the outstanding balance. Anything you pay above the scheduled amount goes straight to principal, so next month's interest is calculated on a smaller balance, and so is every month's after that. The saving compounds, which is why a modest extra amount shortens a loan by much more than you would expect from the arithmetic of the payment alone.
Worked example: $20,000 at 7% over 60 months
The scheduled payment is $396.02 a month and the loan costs about $3,760 in interest if nothing changes.
| Extra per month | Paid off in | Total interest | Interest saved |
|---|---|---|---|
| $0 | 60 months | about $3,760 | — |
| $50 | 53 months | about $3,250 | about $510 |
| $100 | 47 months | about $2,870 | about $890 |
| $250 | 35 months | about $2,120 | about $1,640 |
The first $50 buys seven months. The next $50 buys six more. Getting to $250 removes over two years, but each additional dollar is doing slightly less work than the one before it. That shape matters for how you choose an amount.
How to choose your amount
- 1Work out what is genuinely spare each month rather than what looks impressive. The budget allocation calculator is a quick way to find it.
- 2Keep a small cash buffer first. Paying an extra $300 and then borrowing on a card in month four undoes the whole plan and costs more.
- 3Pick the amount you can automate on the same day as your normal payment, so it is not a monthly decision.
- 4If you have a deadline — a lease ending, a mortgage application, a move — reverse-solve it instead: the payoff tool computes the extra payment a specific debt-free date requires.
- 5Re-check after any income change and adjust once, rather than varying the amount month to month.
Where the extra should go
If you have several balances, the extra payment does the most measurable work on the highest interest rate, because that is where the most interest is being charged per dollar owed. The alternative — smallest balance first — clears accounts sooner and can be easier to stick with. Both are legitimate; the trade-off is worked through in avalanche versus snowball versus extra payments.
Revolving balances behave differently from fixed-term loans, so run those separately with the credit card payoff calculator.
Confirm with your lender that extra amounts are applied to principal. Some servicers hold them as a prepayment of the next scheduled payment by default, which saves nothing.
Frequently asked questions
- Is it better to pay extra monthly or make one lump sum?
- A lump sum applied earlier saves more than the same money spread over a year, because the balance drops sooner. In practice a reliable monthly amount usually beats a lump sum that never quite happens.
- Should I pay extra on debt or save instead?
- Compare the interest rate you are paying with the return you would reasonably expect on savings, and weigh a cash buffer against both. High-rate revolving debt is generally the clearest case for extra payments; a low fixed-rate loan is much less clear-cut. This is a personal trade-off, not a rule.
- Will paying early hurt my credit?
- Closing a loan early can slightly change your credit mix and average account age, but reducing balances generally helps. Any effect is small next to the interest saved.
- Are there prepayment penalties?
- They are uncommon on consumer loans in the US but not extinct. Check the loan agreement before committing to a plan built on early payoff.
Assumptions and limits
Every figure on this page comes from the assumptions stated beside it, calculated with the same formulas the linked tools use. Rates, taxes, insurance and running costs vary by lender, state and household, so substitute your own numbers before acting. Nothing here is a lending decision, a tax opinion, or financial advice.
Read how Answerivo calculators are built or our full disclaimer.