Debt Repayment Calculator

Add your debts and compare the Snowball vs Avalanche methods. See how quickly you can become debt-free and how much interest you will save.

UK households owe over £1.8 trillion in total debt, according to the Bank of England. If you are juggling credit cards, loans, and overdrafts, a structured repayment plan can save you thousands in interest and get you debt-free years sooner. The two most popular methods are the Snowball and the Avalanche.

The Snowball method pays off the smallest balance first, giving you quick wins that build momentum. The Avalanche method targets the highest interest rate first, saving you the most money overall. This calculator compares both so you can choose the approach that suits your personality and finances.

Add all your debts with their balances, interest rates, and minimum payments. The tool shows you a month-by-month payoff schedule for each method, total interest paid, and the date you become completely debt-free.

How it works

  1. Add each debt with the balance, annual interest rate, and minimum monthly payment.
  2. Enter any additional monthly amount you can put towards debt repayment.
  3. Compare the Snowball and Avalanche methods side by side with payoff timelines and interest savings.

Written by the CalcStack team · Last updated April 2026

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Frequently asked questions

What is the debt snowball method?▾
The snowball method focuses on paying off the smallest debt first while making minimum payments on all others. Once the smallest is paid, you roll that payment into the next smallest. It provides quick psychological wins to keep you motivated.
What is the debt avalanche method?▾
The avalanche method targets the debt with the highest interest rate first. Mathematically, this saves the most money on interest over time, but it may take longer to see your first debt fully paid off.
Which is better — snowball or avalanche?▾
Avalanche saves more money on interest, but snowball gives quicker wins. Research shows people are more likely to stick with the snowball method. The best method is whichever you will actually follow through on.
Should I consolidate my debts instead?▾
Debt consolidation can help if you can get a lower interest rate than your current debts. However, be careful of extended terms that increase total interest paid, and avoid running up new debt on cleared credit cards.
How much extra should I pay towards debt?▾
Any extra helps. Even £50-£100 per month above minimums can dramatically reduce your repayment time. Use the calculator to see the impact of different extra payment amounts.
Should I save or pay off debt first?▾
Generally, pay off high-interest debt (above 5-6%) before investing. However, keep a small emergency fund (£1,000) to avoid going into more debt. Always pay at least minimum payments on all debts.
Does this include mortgage debt?▾
You can include mortgage debt, but most financial advisors recommend treating mortgage debt separately due to its lower interest rate and tax implications. Focus on higher-rate consumer debt first.
What if I cannot afford minimum payments?▾
If you cannot afford minimum payments, contact your creditors to negotiate reduced payments or contact free debt advice services like StepChange, Citizens Advice, or National Debtline.
How does the calculator handle interest?▾
Interest is calculated monthly on the remaining balance of each debt. As you pay down balances, less interest accrues, so more of each payment goes towards the principal.
Can I mix strategies?▾
Yes. Some people use a hybrid approach — paying off one or two small debts for quick wins, then switching to the avalanche method for the remaining larger debts.

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© 2026 CalcStack — a Flavoureak UK Ltd product. This calculator provides estimates only and is not financial advice. If you are struggling with debt, contact StepChange for free advice.