DEBTPAYOFF CALCULATOR
Avalanche
Pay highest interest first. Saves the most money.
Snowball
Clear smallest balances first. Stay motivated.
The extra amount you'll throw at debt each month beyond all minimums.
Your Debts
Total: £9,300
Name / Label
Balance (£)
APR (%)
Min Payment
The Debt Avalanche
Mathematically optimal — minimises total interest paid
The debt avalanche is the mathematically correct approach to debt repayment. You pay the minimum on every debt and throw every spare pound at the one with the highest annual percentage rate (APR). Once that debt reaches zero, you roll its minimum payment — plus your extra budget — into the next highest-rate debt. The momentum builds like an avalanche picking up speed.
Because you're always attacking the debt that is costing you the most per pound of outstanding balance, you eliminate interest charges faster than any other strategy. Over the life of your repayment, this almost always results in the lowest total amount paid.
How it works — step by step
List all debts by APR (highest to lowest)
Order your credit cards, loans, and overdrafts by their interest rate — not by balance.
Pay minimums on everything
Make the minimum payment on every single debt to avoid late fees and penalty rates.
Direct all extra money to #1
Every spare pound — after minimums — goes to the highest-APR debt until it's gone.
Roll and repeat
When a debt hits zero, its entire payment is redirected to the next debt on the list.
✓ Saves the most money
By attacking high-interest debt first, you eliminate the most expensive part of your debt load as quickly as possible.
✓ Mathematically optimal
No other strategy consistently produces a lower total interest bill when the same budget is applied.
✗ Slower psychological wins
High-APR debts often have large balances. You may not see a debt cleared for many months, which can feel discouraging.
The Debt Snowball
Psychologically powerful — keeps you motivated with early wins
The debt snowball, popularised by Dave Ramsey, ignores interest rates entirely. Instead, you focus on your smallest balance — regardless of APR — because clearing a debt in full delivers a powerful psychological reward that keeps you engaged in the process.
Research published in the Journal of Marketing Research found that people who focus on clearing one debt at a time — rather than attacking the highest interest — are more likely to eliminate all their debt. The reason: motivation compounds just like debt does. Each cleared debt increases the payment available for the next one, creating genuine momentum.
How it works — step by step
List all debts by balance (smallest first)
Ignore the interest rates. Put the debt with the lowest remaining balance at the top.
Pay minimums on everything else
Keep all other debts current with their minimums to avoid fees and rate increases.
Crush the smallest debt with everything you have
All extra budget goes to that one target. The faster it clears, the faster the snowball rolls.
Roll the freed payment forward
When a debt clears, its minimum plus your extra rolls straight into the next smallest.
✓ Fast early wins
Clearing a small debt completely — even a £300 store card — delivers a real sense of progress that keeps you going.
✓ Higher completion rate
Studies show snowball users are more likely to become fully debt-free because they stay engaged in the process longer.
✗ Costs more interest
By ignoring APR, you may leave your most expensive debt unpaid for longer — costing more in total interest.
Avalanche vs Snowball — Head to Head
| Factor | Avalanche | Snowball |
|---|---|---|
| Priority target | Highest APR debt | Smallest balance |
| Total interest paid | Lower ✓ | Higher |
| Time to first cleared debt | Can be longer | Faster ✓ |
| Psychological motivation | Slower to feel progress | Early wins ✓ |
| Best for | High-rate cards with large balances | Many small debts or low discipline |
| Mathematically optimal? | Yes ✓ | No |
| Completion rate (research) | Lower — harder to stick to | Higher ✓ (Journal of Marketing Research) |
Which Strategy Should You Choose?
Choose Avalanche if...
You have one or two very high-APR debts (over 25%) eating into your budget
You're data-driven and respond to numbers rather than feelings
The interest difference between your debts is large
You're confident you'll stick to the plan regardless of early progress
Choose Snowball if...
You have several small debts that could be cleared quickly
You've struggled with debt motivation or previous plans before
The psychological reward of clearing a debt matters to you
Your interest rates are similar across debts (the difference in total cost is then small)
Bottom line: The best strategy is the one you'll actually follow through on. If snowball keeps you motivated and you stick with it, you'll end up in a better position than someone who chose avalanche and gave up after six months. Run both through the calculator above and see how the numbers compare for your specific debts.
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M Singh CeMAP DipFA · 25+ Years UK Financial Services
Important Information
This calculator is for informational purposes only and does not constitute financial advice or a personal recommendation.
Results are estimates based on the information you provide and may not reflect your actual financial position.
You should consider seeking independent professional advice tailored to your specific circumstances before making any financial decision.