Debt Payoff Calculator
Add your debts and any extra you can put towards them each month to compare the snowball (smallest balance first) and avalanche (highest interest rate first) strategies side by side.
Estimate only. This is an estimate, representative figures, not financial advice. It assumes fixed interest rates, no missed payments and no new borrowing. Speak to a debt adviser (e.g. StepChange or MoneyHelper) if you're struggling with repayments.
Add at least one debt
Enter a balance, APR and minimum payment for each debt to compare payoff strategies.
Snowball vs avalanche: how each is calculated
Both strategies pay the minimum on every debt each month, then put all remaining extra budget towards one target debt. Snowball targets your smallest balance first, clearing debts quickly builds momentum and motivation. Avalanche targets your highest APR first, since interest is minimised by attacking the most expensive debt first, avalanche is mathematically guaranteed to cost the same or less in total interest than snowball. Once a debt is paid off, its minimum payment rolls into the extra budget for the next target, so payments snowball as you go, both strategies usually clear all your debts in a similar number of months, but avalanche typically saves you money along the way.
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Track this on TrackBritainSnowball and avalanche, and why the choice is not obvious
Both strategies do the same thing with the minimums: you keep paying every debt's minimum every month, always. The only question is where the spare money goes.
Avalanche targets the highest interest rate first. It is mathematically optimal, because every spare pound goes against the debt costing the most to carry, so it always clears the total for the least interest and usually fastest.
Snowball targets the smallest balance first. It costs more in arithmetic and it wins on something arithmetic does not measure: an account closed is visible progress, and the freed-up minimum payment rolls into the next debt, which accelerates things in a way you can see. For people who have abandoned repayment plans before, that matters.
The honest framing is that avalanche is the better plan and snowball is the better plan you will actually finish. The right answer depends on which failure you are more likely to suffer.
What the difference is actually worth
On the worked example below, £7,600 across three debts with £150 a month spare, avalanche costs £2,388.48 in interest against snowball's £2,870.13 and finishes two months sooner. The difference is £481.65.
That is a real sum and it is not a transformative one. If snowball is the difference between sticking to a plan and giving up in month four, £481.65 is a reasonable price for finishing at all.
The gap widens when the rate spread between debts is large, and narrows when they are similar. It also narrows when your smallest debt happens to be your most expensive, in which case the two strategies produce the same order and the choice is moot. Run both before assuming it matters.
What matters far more than the ordering is the amount. Adding to the monthly figure moves the outcome much more than choosing between strategies, which is why the calculator models extra-payment scenarios alongside the two orderings.
The ordering is not always what you would expect
In the example below, avalanche clears the credit card first, as you would expect at 29.9%, and then the overdraft rather than the car loan, even though the car loan carries the higher rate of the two remaining.
That is not a quirk of the model, it is what actually happens. Minimum payments keep landing on every debt throughout, so a small balance can clear itself through its own minimum while the spare money is aimed elsewhere. The payoff order the simulation reports is the order debts actually disappear, not a ranking of your intentions.
It is worth knowing because it changes what the plan feels like. Even on a strict avalanche you will usually see a small debt vanish early, which is the psychological benefit people assume only snowball delivers.
Before you start the plan
Check whether a 0% balance transfer would beat both. Moving credit card debt to an interest-free period for a fee of around 2 to 3% usually costs far less than any repayment ordering saves, and it changes the arithmetic more than the strategy choice does. Our balance transfer calculator prices it.
Clear the most expensive credit first even if it is not on this list. An overdraft at 39.9% or a payday-style loan outranks everything here, and both are easy to leave out of a debt plan because they do not feel like debts.
Keep a small emergency buffer rather than throwing every spare pound at the balances. Without one, the next unexpected bill goes back on a credit card and the plan resets. A few hundred pounds held back is not inefficiency, it is what stops the cycle restarting.
And do not let the plan require money you do not have. An extra payment you cannot sustain produces a plan you abandon, which is worse than a slower plan you complete.
When a repayment plan is the wrong tool
This calculator assumes the minimums are affordable and there is something spare. If the minimums alone are not affordable, no ordering fixes that and you need a different conversation.
Free, independent debt advice is available from StepChange, Citizens Advice and National Debtline. None of them charge, none of them sell a product, and they can negotiate with creditors on your behalf, including for interest to be frozen, which does more than any strategy on this page.
Fee-charging debt management companies offer nothing the free services do not, and take a share of money that would otherwise clear your debts.
If you are paying more in interest and charges than off the balance, FCA persistent-debt rules require your card issuer to contact you with a plan to repay within a reasonable period. That letter is worth engaging with rather than filing.
Worked example: £7,600 across three debts, £150 a month spare
An overdraft, a car loan and a credit card, with the smallest balance deliberately carrying the lowest rate so the two strategies genuinely diverge. These are the exact figures this calculator returns.
| Overdraft | £600 at 6.9%, £25/mo minimum |
|---|---|
| Car loan | £2,000 at 18.9%, £70/mo minimum |
| Credit card | £5,000 at 29.9%, £125/mo minimum |
| Extra available each month | £150.00 |
| Snowball, time to debt-free | 29 months |
| Snowball, total interest | £2,870.13 |
| Snowball, total repaid | £10,470.13 |
| Avalanche, time to debt-free | 27 months |
| Avalanche, total interest | £2,388.48 |
| Avalanche, total repaid | £9,988.48 |
| Interest saved by avalanche | £481.65 |
Avalanche saves £481.65 and finishes two months earlier. Worth having, not life-changing, and worth trading away if snowball is what gets you to the end. Note the avalanche order too: credit card, then overdraft, then car loan. The overdraft clears second despite the lowest rate, because its own minimum payment finishes it off while the spare money is aimed at the card.
Frequently asked questions
- What is the difference between the debt snowball and debt avalanche?
- Both pay every minimum every month; the difference is where the spare money goes. Avalanche targets the highest interest rate first, which always costs the least in total. Snowball targets the smallest balance first, which clears accounts sooner and gives visible progress. Avalanche is mathematically better; snowball is the one more people finish, and finishing is what actually clears the debt.
- How much does the avalanche method actually save?
- Less than people expect, usually. On £7,600 across three debts with £150 a month spare, avalanche costs £2,388.48 in interest against snowball's £2,870.13 and finishes two months sooner, a difference of £481.65. The gap widens when the rate spread between your debts is large and narrows when they are similar. Run both before assuming the choice matters.
- Which debt should I pay off first?
- The highest interest rate, if you are purely minimising cost. The smallest balance, if you need visible progress to stay with the plan. Whichever you choose, keep paying every minimum on everything else, because a missed minimum triggers fees and a credit-file marker that costs far more than any ordering saves. And check for anything expensive you have left off the list, such as an overdraft.
- Does paying off debt early save money?
- Yes, and the effect is larger than it looks because interest accrues on the balance every month it remains. Clearing a balance three months early removes three months of interest on that whole balance. Regulated credit agreements can be settled early at any time under the Consumer Credit Act, with a statutory rebate of interest not yet incurred, though the lender may add up to 58 days of interest on longer agreements.
- Should I use a balance transfer instead?
- Check it first, because it usually changes the arithmetic more than the strategy does. Moving credit card debt to a 0% period costs a fee of roughly 2 to 3% and removes interest entirely for the promotional term, which typically beats anything a repayment ordering can save. Divide the balance by the number of 0% months to find the payment that actually finishes it, and do not spend on the transfer card.
- Should I save or pay off debt first?
- Pay off debt costing more than your savings earn, which is almost all consumer credit at current rates, but keep a small emergency buffer rather than throwing every spare pound at balances. Without one, the next unexpected bill goes straight back on a credit card and the plan resets. A few hundred pounds held back is not inefficiency, it is what stops the cycle starting again.
- Why did a low-interest debt clear before a higher-rate one on avalanche?
- Because minimum payments keep landing on every debt throughout. A small balance can finish itself off through its own minimum while the spare money is aimed at the most expensive debt. The payoff order shown is the order debts actually disappear, not a ranking of priority. It also means even a strict avalanche usually gives you an early win, which is the benefit people assume only snowball offers.
- What if I cannot afford the minimum payments?
- Then no repayment ordering helps, and this is the point to get free independent advice from StepChange, Citizens Advice or National Debtline. None of them charge and none sell a product, and they can negotiate with creditors including for interest to be frozen, which does more than any strategy here. Avoid fee-charging debt management companies, which offer nothing the free services do not.
Also known as: debt calculator · debt repayment calculator · debt payment calculator · pay off debt calculator · debt calculator UK · debt snowball calculator · debt reduction calculator · calculate debt repayment
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