Snowball vs avalanche
Not a lender · illustrative only.Figures are examples, not offers or advice.
Compare smallest-balance-first (snowball) with highest-rate-first (avalanche) on three debts — months and interest side by side.
Methodology: how this is calculated · Last checked:
Your inputs
Debt 1
Debt 2
Debt 3
Results
Snowball
Smallest balance first
Debt-free by
—
2 years 5 months
- Total interest
- £1,554
- Total paid
- £9,254
Order: Card B → Card A → Personal loan
Avalanche
Highest rate first
Debt-free by
—
2 years 5 months
- Total interest
- £1,471
- Total paid
- £9,171
Order: Card A → Card B → Personal loan
Both finish in the same month · avalanche pays £83 less interest.
Snowball clears a balance sooner, which some people find easier to stick with. Avalanche targets the highest rate, so it usually pays the least interest. Dates assume the first payment is next month.
Show chart as a table
| Month | Snowball interest so far | Avalanche interest so far |
|---|---|---|
| 6 | £581 | £575 |
| 12 | £1,044 | £1,010 |
| 18 | £1,364 | £1,291 |
| 24 | £1,517 | £1,434 |
| 29 | £1,554 | £1,471 |
Method: Capital-and-interest reducing balance; monthly rate = APR ÷ 12. Representative APR on UK credit ads may include fees — we model fees separately unless stated. Extra (plus freed minimums) goes to the target debt each month.
Most people next
Illustrative only — not personalised advice, not a credit offer, and not an FCA-regulated recommendation. LoanCalc Lab is not a lender or broker. Check the lender’s pre-contract information for the APR, fees and early settlement terms. Rates and fees change. Full calculator disclaimer.
How this is calculated
Step by step, exactly as the calculator above works it out. Nothing is sent to a server — the sums run in your browser.
- Debts with a zero or blank balance are ignored. Both strategies then run month by month from the same starting balances.
- At the start of each month the active debts are sorted. Snowball: smallest balance first (ties go to the higher rate). Avalanche: highest rate first (ties go to the smaller balance). The first debt in the list is the target.
- For every debt, interest = balance × annual rate ÷ 100 ÷ 12 is added, then the minimum payment is taken off. The target also receives your extra amount plus any minimums freed up by debts already cleared.
- No payment is allowed to exceed the balance. If the target clears part-way through a month, the unused part of that month’s extra is not moved to another debt until the next month.
- When a debt reaches zero, its minimum joins the freed-up pool for the following months.
- The run stops when every balance is cleared or after 720 months. Interest difference = snowball interest − avalanche interest.
Equations & assumptions
Each month apply minimums to all debts; put extra (plus freed minimums from cleared debts) on the target debt. Snowball targets lowest balance; avalanche targets highest rate.
- Capital-and-interest reducing balance; monthly rate = APR ÷ 12. Representative APR on UK credit ads may include fees — we model fees separately unless stated.
- Interest accrues monthly on each remaining balance before payment.
- Three debt inputs by default; needs at least two debts with balance and minimum payment.
Using this calculator well
When to use it
Use this when you have two or more debts and a fixed amount each month to put towards them. It runs both payoff orders on your own balances: the avalanche, which targets the highest rate first, and the snowball, which clears the smallest balance first. You see the interest and time each takes, so you can judge whether the quick wins of the snowball are worth any extra cost for you.
Common errors to avoid
- Setting the monthly budget below the total of your minimum payments; the plan cannot work.
- Entering promotional 0% rates without the date they end, which can flip the ranking.
- Assuming minimums stay fixed; card minimums usually fall as the balance falls.
- Taking on new borrowing during the plan, which no payoff order can outrun.
- Treating the result as fixed. Re-run the comparison whenever a balance is cleared, a rate changes or your budget moves, because the best order can change too.
UK traps and limits to check
- Priority debts first. Council tax, rent or mortgage, energy and court fines carry more serious consequences than cards and loans. MoneyHelper explains how to prioritise your debts.
- Promotional rates end. A 0% card is modelled at the rate you enter for the whole plan. If a promotion ends, re-run with the rate it reverts to. MoneyHelper’s balance transfer guide covers fees of around 2–4%.
- Minimum payments change. Card minimums usually fall as the balance falls; this planner keeps them fixed, which is closer to setting a fixed Direct Debit. Paying only the minimum for 18 months can trigger persistent-debt contact from the card provider — see managing credit well.
- Early settlement fees. On most regulated UK personal loans you can repay part or all of the loan early (Consumer Credit Act 1974, s94). On a fixed-rate loan the lender may charge compensation, capped at 1% of the amount repaid early (0.5% if 12 months or less remain), and generally only where early repayments exceed £8,000 in a 12-month period. The rebate rules sit in the Consumer Credit (Early Settlement) Regulations 2004; MoneyHelper explains them in plain English in repaying a personal loan early. Ask the lender for a settlement figure rather than relying on any schedule.
- Variable vs fixed. These calculators hold the rate constant for the whole term, which matches a fixed-rate loan. Some loans and most credit cards are variable, so the real figure can move — for example when the Bank of England Bank Rate changes and a lender passes it on. Re-run the numbers with a higher rate to see how much headroom you have.
General information only, not advice. LoanCalc Lab is not a lender or broker and does not recommend borrowing.
Notes & FAQs
How do I map my debts into this planner?
List each unsecured balance with its rate and the minimum you must pay. Put spare cash after minimums in the extra field. The default three-debt EXAMPLE (£2,500 at 24.9%, £1,200 at 19.9%, £4,000 at 9.9%, plus £100 extra) is a starting template only.
Where do fees fit in snowball vs avalanche?
This planner does not model a new consolidation fee. If you are comparing payoff strategies against a consolidation loan with a fee, run the consolidation break-even tool as well — a fee can reorder lifetime-cost rankings.
What are these months and interest figures not?
Not a lender schedule, not credit counselling, and not a promise that minimums will stay fixed. Rate changes, missed payments and new borrowing are outside the model.
When should I not use this planner?
Do not use it for mortgages, or when you cannot meet minimums on every debt. Priority bills and arrears need a different process before discretionary payoff maths.
Which should I choose?
Avalanche usually costs less interest. Snowball can be easier to stick with because balances clear sooner. Run both with your numbers.
Why might both strategies show similar months?
With a large extra payment relative to balances, both paths can finish in a similar number of months while interest still differs. Read the interest columns, not only the month count.
What happens when a debt is cleared?
Its minimum is treated as freed cash and rolled onto the next target. That is how both snowball and avalanche accelerate after each clearance.
Can I mix strategies mid-way?
In real life yes; this page compares the two pure rules side by side. If you switch later, re-enter the remaining balances and run again.
Why do both strategies sometimes give the same answer?
If the smallest balance also has the highest rate, both methods pick the same target every month. With no extra payment, minimums alone can also clear debts in the same order, so the gap narrows to a few pounds.
Can I include a 0% balance transfer card?
Yes — enter 0% and it will accrue no interest. Avalanche will then target it last. Remember the planner does not know when the 0% period ends.
Related tools & guides
Who this planner is for
Use it when you will keep several debts and have spare cash after minimums. Snowball clears the smallest balance first; avalanche clears the highest rate first. Not a consolidation decision — that is the consolidation break-even tool.
Avalanche usually costs less interest; snowball clears the first debt sooner. A consolidation fee can reorder which path is cheapest in cash. Guide: snowball vs avalanche. Disclaimer.
Case study: three debts and £100 a month spare
A borrower has Card A (£2,500 at 24.9%, minimum £75), Card B (£1,200 at 19.9%, minimum £40) and a personal loan (£4,000 at 9.9%, minimum £110), plus £100 a month spare. Snowball clears Card B first, then Card A, then the loan. Avalanche clears Card A first, then Card B, then the loan. Both finish in 29 months.
Avalanche costs about £1,471 in interest; snowball about £1,554 — roughly £83 more, in exchange for clearing a card sooner. If the spare amount rises to £250, avalanche finishes in 19 months with about £901 interest and snowball in 20 months with about £981, a gap of about £80. With no spare money at all, both paths clear the debts in the same order and the gap narrows to about £8. The maths favours avalanche; whether the earlier win is worth about £80 is a personal call. Either way, keep paying every minimum on time.
Edge cases
Blank or zero rows are ignored, so you can compare two debts. Negative balances, rates or minimums show a message. If a minimum is at or below that debt’s monthly interest and the extra cannot cover it, the planner says the debts don’t clear instead of showing a result.
Sources for product-norm wording only: MoneyHelper — credit; FCA consumer credit. Case-study figures are EXAMPLES produced by this calculator’s own code, not a quote or an offer. Last checked 24 October 2026.