Extra Debt Payment Calculator

How it works

Every monthly payment on a credit card or loan splits in two. Part covers the interest your creditor adds for the month, and the rest goes to principal. The interest rate and the balance set that first part, so a dollar added above the minimum skips it and lands on principal.

A smaller balance means less interest next month, which frees more of the following payment for principal. That effect builds month after month. The calculator runs the payoff twice, once at your payment and once with the extra, using the payoff-time formula:

• B — the balance owed
• i — the monthly interest rate (APR ÷ 12)
• P — the monthly payment, with or without the extra
• n — months until the balance clears

Compare the two runs on the default numbers. A $12,000 credit card debt at 22% APR takes 73 months at $300 a month and costs about $9,827 in interest.

Push the payment to $400 and the same debt clears in 44 months, 29 months sooner, with interest of about $5,581. That extra $100 a month is worth roughly $4,246.

✓ Every result is checked against independent reference math. See how we test the calculators →

How to use this calculator

1. Enter the balance you currently owe on the debt.
2. Add the interest rate, using the APR from your statement.
3. Enter the monthly payment you make now, before any extra.
4. Type the extra amount you can add each month.
5. Compare the two payoff months and the two interest totals.
6. Adjust the extra up or down until the payoff date looks workable.

A worked example: $100 extra on a $12,000 card

You owe $12,000 on a card at 22% APR and you have been paying $300 a month. At that pace the balance takes 73 months to clear. The question is what one small change does.

Add $100 each month, so you send $400 instead of $300, and the payoff drops to 44 months. That is 29 months sooner, and because the debt disappears faster it stops collecting interest. You keep $4,246 that would have gone to the lender.

Run your own balance and rate through it. Whatever you can spare bends the curve, and seeing the interest saved in real dollars makes the choice a lot easier to stick with month after month.

Where can you find the extra payment?

The extra does not have to be large or wait on a raise. Most debtors find it in money that already moves through the checking account each month.

• Round the payment up: bumping $300 to a round $350 or $400 is easy to remember, and it cuts months off a high-rate balance.
• Send windfalls straight to principal: a tax refund or a work bonus works like the extra here, just in one lump. Check the effect of a single lump sum first.
• Confirm it hits principal: some creditors put an overpayment toward next month's bill instead of the balance. Tell your creditor, or set it in your online banking, that anything above the minimum goes to principal.

Why does starting sooner beat paying more later?

Every extra dollar you send cancels the interest that dollar would have generated for every remaining month of the debt. That is why timing matters as much as amount. An extra $100 started today works against the balance for the whole payoff, and the same $100 begun a year from now saves noticeably less.

So a small extra started now often beats a larger one you keep putting off. On a 22% card, each added dollar cancels interest at 22% a year. That is a guaranteed return no savings accounts or short certificate of deposit can match.

Consistency is what makes the projection hold. It assumes the extra arrives every month, so an extra you pay only when you remember drifts back toward a minimum-payment schedule.

Set up autopay for the higher amount once and leave it. You can raise it later, but the months you spend waiting for a rounder number do not come back. If a calendar date is easier to hold in mind than a month count, check the date your balance hits zero.

How different extras compare on the same balance

It helps to see a few extras side by side on one balance. Start from the default $12,000 at 22% with a $300 payment. That pace alone runs 73 months and roughly $9,827 in interest.

• Extra $50 ($350 total): paid off in about 55 months, interest around $7,081.
• Extra $100 ($400 total): paid off in about 44 months, interest around $5,581.
• Extra $200 ($500 total): paid off in about 32 months, interest around $3,958.

That first $50 does the most work per dollar, knocking about 18 months and $2,700 of interest off the baseline. Stretching to $100 lifts the saving to 29 months and over $4,200, because a 22% rate keeps every added dollar cancelling interest for years.

The same logic scales down. If $100 is out of reach this month, $20 or $30 on top still lands entirely on principal. Enter your own balance, rate and payment above, then try two or three extras and watch what each does to the payoff month.

Which debt should get the extra payment?

This calculator handles one balance at a time, so a debtor juggling several has to choose. Rank them by interest rate first. A card at 22% and a personal loan at 11% are not close, and the card should take the money.

• Highest rate first: paying the most expensive balance saves the most interest overall, which is the avalanche order.
• Smallest balance first: the Debt Snowball clears one account quickly and keeps people going, so comparing the two orders is worth a minute.
• Low-rate debt last: a mortgage, most student loans, and a home equity line of credit sit well below card rates, so extra money there does less work.

Home equity loans and a HELOC are cheap partly because your house secures them. Missing payments on either risks the house, not just your credit. That risk is one reason a debt consolidation loan is not automatically a win, so run the break-even on consolidating before you move card debt onto home equity.

Should the extra go to debt or savings?

Paying extra carries opportunity costs, since that money cannot also sit in an investment. But the comparison is simpler than it looks. Compare what the debt charges you with what the cash would earn.

A 22% card costs more than almost any savings option pays. High-yield savings accounts and a money market fund pay a few percent, and inflation takes part of that. No ordinary investment strategy competes with cancelling a 22% finance charge.

Keep a small starter emergency fund anyway. Hold it in a savings account you can reach in a day, not the checking account where it gets spent.

Without that cushion, a single car repair goes back on the card and undoes months of extra payments. Once the expensive credit card debt is gone, redirect the same monthly amount into savings.

When extra payments are not enough

Sometimes the payment you can afford will not clear the balance in any reasonable time. If the minimum barely covers interest and there is nothing left to add, extra payments are not the right tool.

• Nonprofit credit counseling: a counseling agency can set up a debt management plan and often gets creditors to cut your rate. The CFPB explains how to find legitimate help.
• Debt settlement: a settlement pays creditors less than the full balance, but it marks your credit report. The forgiven amount can also count as income the IRS taxes.
• Bankruptcy: Chapter 7 wipes most unsecured debt, while Chapter 13 bankruptcy sets a court-supervised repayment plan running three to five years.

Bankruptcy does not erase everything. Child support and alimony survive a filing, and so do recent income taxes and most student loans.

A Chapter 7 or Chapter 13 case also stays on the credit report for years and drops the FICO score sharply. Credit counseling is the cheaper first stop, and debt settlement or bankruptcy the last resort.