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UK · 2026/27

Multi-Debt Snowball vs Avalanche Planner

Add multiple debts and compare snowball and avalanche repayment plans, payoff dates, total interest and the effect of extra monthly payments.

Last reviewed: 4 August 2026Source: MoneyHelper — reducing borrowingUpdated every: methodology change
Multi-Debt Snowball vs Avalanche Planner · UKLoans & Credit

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Rates & sources

Month-by-month illustration using only the balances, APRs, minimum payments and extra payment entered. It does not reproduce lender statement dates, daily interest, changing minimums, fees or promotional-rate expiry.

Avalanche priorityhighest APR first
Snowball prioritysmallest balance first
Minimum paymentsentered by you
Maximum projection50 years

Source: MoneyHelper — reducing borrowing — check the linked guidance and any live quote before acting.

When to use this calculator

  • Before comparing lenders, brokers, or repayment options.
  • When you want to test how a different deposit, rate, or term changes affordability.
  • When you need a quick estimate before using a formal quote or agreement in principle.
  • When you are stress-testing your budget against a potential rate rise to see the impact on monthly payments.
  • When you want to understand the full cost of borrowing — not just the monthly figure — before you commit.

A realistic UK planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

Total debt (£)

13000

Approximate weighted APR (%)

5%

Total monthly payment (£)

6

After entering these figures, review approximate payoff time, approximate interest and approximate total paid together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.

How to read your results

Approximate Payoff Time

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

Approximate Interest

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

Approximate Total Paid

This is the headline outcome of the calculation, but it is most useful when read alongside the supporting metrics below it rather than in isolation. Try changing one input at a time and watching how this total moves to understand which driver has the biggest impact.

Status

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

Method & assumptionsAuthoritative sources

This planner lets you enter up to ten credit cards or loans and keeps the same overall monthly payment budget as individual balances are cleared. The avalanche option sends spare money to the highest APR; the snowball option sends it to the smallest balance. Both continue the minimum payments entered for the other balances.

The month-by-month estimate adds one-twelfth of the entered APR before applying payments. Real lenders may calculate interest daily, change rates, apply fees or use minimum-payment formulas rather than fixed amounts. Promotional rates and early-settlement terms are not modelled.

If the entered budget does not clear the balances within 50 years, the tool reports that instead of inventing a payoff date. Anyone unable to maintain contractual payments should use free, impartial debt help rather than treating this illustration as advice to borrow or consolidate.

Common mistakes

  • !Mixing up loan amount and property value, which can distort affordability and LTV.
  • !Using a headline rate but forgetting fees, insurance, taxes, or repayment type.
  • !Testing only one term length instead of comparing the payment and total cost together.
  • !Forgetting that a repayment mortgage and an interest-only mortgage produce very different monthly figures and total costs.
  • !Not accounting for the impact of a rate revert after an introductory fixed period ends, which can sharply increase payments.

What to do next

  • Run a second scenario with a higher rate or shorter term so you can see the downside clearly.
  • Compare the result with an affordability or overpayment calculator before applying.
  • Use the related guides below to understand trade-offs before you request live quotes.
  • Note down the monthly payment and total interest for your two or three strongest scenarios so you have a clear comparison ready when you speak to a broker.
  • Check whether making a modest overpayment each month would reduce total interest significantly — run the overpayment calculator next to find out.

Frequently asked

The avalanche method directs extra money to the balance with the highest APR while maintaining the entered minimum payments on the others. It will normally minimise interest when the payment assumptions remain unchanged.

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