Debt snowball calculator
List your debts, add whatever you can pay above the minimums, and see the order to clear them and how long the whole thing takes.
How this is calculated
Every debt is charged interest each month, then the minimum payment is made on all of them, then everything left over is thrown at one target debt until it clears.
Once a debt clears, its minimum payment joins the pot and goes at the next target. That is the snowball: the amount going at the debts stays the same while the number of debts falls, so each one clears faster than the last.
Snowball orders by smallest balance, avalanche by highest interest rate. Avalanche is always cheaper on paper. Snowball clears a whole debt sooner, which is why more people actually finish it.
The comparison at the bottom runs the same debts on minimum payments only, which is usually the number that makes the case for doing anything at all.
Rates used · 2026/27
| Snowball | smallest balance first |
| Avalanche | highest APR first, mathematically cheapest |
| Minimum payments | assumed fixed, not a falling percentage |
| Free debt advice | StepChange and National Debtline, both free |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
Four debts totalling £11,700 with £335 of minimums and £150 extra a month clear in 2 years 6 months for £2,515 of interest, in the order store card, overdraft, credit card, car loan. Avalanche order costs £2,438, saving £77. On minimum payments alone the same debts would take 15 years 4 months and cost £12,230.
Common questions
Snowball or avalanche?
Avalanche costs less. Snowball is easier to stick with because you see a debt disappear sooner. The difference between them is usually smaller than the difference between doing either one and doing nothing.
What if I cannot afford the minimums?
Then this calculator is the wrong tool and free debt advice is the right one. StepChange and National Debtline are both free, independent and will not charge you for a plan.
Should I clear debt or save first?
Generally clear anything charging more than your savings rate, which is almost always the case with cards and overdrafts. Keeping a small emergency buffer alongside is still sensible.
Does this assume I stop borrowing?
Yes. Any new spending on the same cards pushes the dates back, and the calculation assumes the balances only go down.