Debt Payoff Calculator: Payoff Date and Total Interest

Enter your balance, interest rate and monthly payment to calculate your debt payoff time, total interest and the effect of paying more.

Last updated: October 3, 2026

Example: the calculation with the default values

The defaults are example values, not an average. Enter your own numbers and press “Calculate” to run it with yours.

Until you are out

23 months

Paid in total

$2,243

Of that, interest

10.8%

Outstanding	$2,000
Your payment per month	$100
Months until it is paid off	23.00
Paid in total	$2,243
Of that, interest	$243

Assumptions behind this calculation

The rate you enter is read as a nominal APR and divided by twelve, the way a card statement builds its periodic rate. Taking the twelfth root instead would understate the very number this is about.
Calculated month by month in whole cents: interest on first, payment off second. That is the order a bank posts in, and it is the order you can check.

How we calculate

The annual rate is turned into a monthly rate: read as an APR and divided by twelve. Then the balance is worked month by month in whole cents: interest on the open balance first, the payment off second, until nothing is left.

Counted are the months until payoff, the total paid and the interest in it. If the payment is no higher than the first month’s interest, the debt is never paid off, and the calculator says so. An extra amount runs as a second calculation with the higher payment.

The reasoning behind these numbers, with sources, is in the article: Pay Off Debt or Save? Compare Interest Rates.

Frequently asked

How long will it take to pay off my debt?

With this calculator’s defaults – $2,000 owed, 12 percent APR, $100 a month – you are out after 23 months and pay $2,243 in total, $243 of it interest.

How is the interest calculated?

The rate you enter is read as a nominal APR and divided by twelve, the way a card statement builds its periodic rate. Taking the twelfth root instead would understate the very number this is about. Calculated month by month in whole cents: interest on first, payment off second. That is the order a bank posts in, and it is the order you can check.

What if my payment is too small?

If the payment is no higher than the first month’s interest – $20.00 in the example –, the debt is never paid off: the balance grows every month. The calculator then says so instead of inventing a payoff date.