Debt payoff calculator: snowball vs avalanche

How to use the calculator

1. Choose your currency, then list each debt under Your debts: a Name, the Balance, the APR % and the Minimum you must pay each month. The “Add a debt” button adds another row (up to 12), and × removes one.
2. Under Your payments, the calculator adds up your minimums. Enter what you can pay on top in “Extra on top of the minimums, each month”.
3. The “Your plan” box shows how long the cheaper order takes, the interest under each method, what the snowball’s quick wins cost, and the interest if you paid only the minimums. The table underneath shows the month each debt clears.

The calculator starts with three sample debts: a credit card of 6,000 at 24.9% (minimum 150), a personal loan of 1,800 at 9.9% (minimum 60) and a store card of 2,600 at 29.9% (minimum 75). The extra payment starts at 150 a month.

How the numbers are worked out

Every month, each debt is charged interest of balance × APR ÷ 12. Then the calculator:

1. adds that interest to each balance
2. pays every minimum
3. sends the rest of the monthly budget to the target debt (the smallest balance for the snowball, the highest APR for the avalanche), with any leftover going to the next target in the same month
4. keeps a cleared debt’s minimum in the budget, so it rolls on to the next target

It stops when every balance reaches zero, or after 600 months. In US dollars, the defaults give a budget of $285 in minimums plus $150 extra, so $435 a month. Month 1 charges $124.50 of interest on the credit card ($6,000 × 24.9% ÷ 12), $14.85 on the personal loan and $64.78 on the store card. The avalanche targets the store card, the highest rate, so it gets its $75 minimum plus the $150: $2,600 + $64.78 − $225 leaves $2,439.78. The snowball targets the personal loan, the smallest balance: $1,800 + $14.85 − $210 leaves $1,604.85.

“Minimums only” means each debt gets its own minimum and nothing rolls on when one is cleared.

Snowball vs avalanche, using the sample debts

The two methods split on the sample debts because the smallest balance, the personal loan, also has the lowest rate. The snowball clears it in month 9, five months before the avalanche clears its first debt (the store card, in month 14). That early win costs $553.53 more interest, the figure under “What the snowball’s quick wins cost”, and the snowball finishes a month later, in month 34.

If the smallest debt also had the highest rate, both methods would start with it and the quick win would cost nothing. Edit the rates in the calculator and the gap moves with them.

The amount you pay moves the date more than the order does. Rolling cleared minimums on, with no extra at all, clears the sample debts in 69 months instead of 87. Adding $150 a month brings it to 33, and $300 a month to 22.

Which to choose

In every set of debts we ran for this page, the avalanche cost the same as the snowball or less. Less money sits at the highest rate, for less time. The snowball’s case is behavioral: a cleared debt is one fewer bill, and an early result can make the plan easier to keep going. If that’s worth something to you, the calculator shows the price as “What the snowball’s quick wins cost”.

Scroll is education, not advice. Our lessons and calculators explain how money works in general. They don’t know your circumstances, so they can’t tell you what to do with yours. For that, speak to a qualified, regulated adviser in your country.

The minimum-payment trap

A minimum that barely covers the interest keeps a debt alive for years. A $3,000 card at 22.9% charges $57.25 of interest in its first month, so any fixed payment of $57 or less never clears it; the calculator warns you when that happens.

If your card sets its minimum as a percentage of the balance (your statement says how), the minimum shrinks as you pay down, and paying only that takes longer than the fixed amounts above.

That 22.9% sits close to recent averages. The Federal Reserve’s G.19 release of 7 October 2026 put the average rate on US card accounts that were charged interest at 22.15% in the second quarter of 2026 (20.94% across all accounts). Its preliminary figure for August is 22.36%. In the UK, the Bank of England’s effective rate on interest-charging credit cards was 21.55% in August 2026, up from 21.45% in July.

Balance transfers and consolidation

A 0% balance transfer isn’t free if there’s a transfer fee. On the sample’s $6,000 card, a 3% fee is $180. To try one in the calculator, add the fee to the balance and set the APR to 0%. With the sample debts, the avalanche’s interest falls from $3,617.70 to $699.89, plus the $180 fee. The order changes too: at 0% the card goes last, and the avalanche clears it in month 26 (the snowball in month 27). If the 0% period ends sooner, interest restarts on what’s left, which the calculator doesn’t model.

A consolidation loan replaces several debts with one. It saves interest only if its rate beats the mix of rates it replaces. Rolling all three sample debts ($10,400) into one loan at 11.9% and paying the same $435 a month costs $1,529.86 over 28 months, against the avalanche’s $3,617.70, because most of the balance moves from 24.9% and 29.9% down to 11.9%. The personal loan’s 9.9% would rise, though, and a loan only helps if the cards it clears stay clear. A lower payment stretches it out: $300 a month on that loan takes 43 months and $2,407.27 of interest.

Where the emergency fund fits

Putting every spare dollar on debt leaves nothing for the next car repair. That repair then goes back on a card. Each $1,000 left on a card at 22.15% costs about $18 a month in interest, while $1,000 at the FDIC’s national average savings rate of 0.37% (21 September 2026) earns about 31 cents. A small starter fund is one way to avoid that; the emergency fund calculator works out one month of your essential costs and when you’d reach it. Our guide on whether to pay off debt or save first covers the trade-off in more detail.

A UK example

Tomasz is made up; his numbers come from the calculator. He owes £8,300: car finance of £1,800 at 7.9% (minimum £150), a credit card of £2,500 at 22.9% (minimum £75) and a store card of £4,000 at 29.9% (minimum £120). His minimums come to £345, and he can pay £200 on top, so £545 a month.

The avalanche goes store card, credit card, car finance; the snowball takes them in reverse. Both finish in month 19. The snowball’s win in month 6 costs £280.13, and paying only the minimums would take six years and one month, with £6,248.18 of interest.