Debt Payoff Calculator
Enter what you owe and what you pay each month. The second figure is the one worth playing with: adding even a modest amount to the payment usually removes years, because every extra dollar goes straight against principal.
Your inputs
Your result
Formula
Why an extra payment does so much
Interest is charged on the balance. The scheduled payment covers that month's interest first, and only what is left reduces the principal. An extra payment skips that queue entirely — all of it goes against principal, and it stops accruing interest for the whole remaining term.
That is why an extra hundred a month on a high-rate debt often removes years rather than months. The saving compounds in your favour.
When the payment is too small
If the monthly payment does not exceed the interest accruing, the balance grows no matter how long you pay. The calculator flags this rather than showing a number, because there is no answer to give: the debt is not being repaid at all. Raising the payment above the monthly interest is the only fix.
Snowball or avalanche
With several debts, the arithmetically optimal order is highest rate first — the avalanche. It always costs less in total interest. The snowball, smallest balance first, costs more but clears individual debts sooner, and the visible progress helps some people keep going. The best method is the one you actually finish.
Watch for the rate changing
Promotional rates expire. A balance-transfer card at zero percent reverts to a normal rate at the end of the promotional window, and anything still outstanding then starts accruing at the full rate. Plan the payment so the balance is gone before that date, not shortly after.
Frequently asked questions
Should I pay off debt or invest?
Compare the debt rate against a realistic after-tax investment return. High-rate consumer debt is very hard to beat with investing, so clearing it first is usually the stronger move. Low-rate debt is a closer call.
Does paying extra hurt my credit score?
No. Reducing balances generally helps, particularly on revolving credit where utilisation is a factor. Closing the account afterwards can have a small effect by reducing your available credit and average account age.
Will my lender apply extra payments to principal?
Usually, but not always automatically. Some lenders treat an overpayment as prepaying the next instalment instead, which saves far less. Ask them to apply it to principal and check the next statement.