UK Debt Snowball Calculator

Enter your debts to see your exact debt-free date. Free, no signup needed.

Built by Richard Bate, founder of TrySnowball

How the Debt Snowball Method Works

The debt snowball method is a debt repayment strategy that attacks your smallest debt first, regardless of interest rate. You make minimum payments on all your debts, then throw every extra pound at your smallest balance. When that debt is eliminated, you take its entire payment (minimum + extra) and roll it into the next smallest debt - creating a growing "snowball" of payments.

This method works because motivation matters more than maths. Each debt you clear is a psychological win that keeps you going. In the UK, where credit card rates often exceed 20% APR, staying motivated to pay off debt is crucial - and the snowball method delivers quick victories that maintain momentum.

Quick Example: If you have three debts (£800, £2,500, £5,000) and £100 extra per month, you'll pay off that £800 debt in about 8 months. Then that payment rolls into the £2,500 debt, dramatically accelerating your progress.

Snowball vs Avalanche: which saves more?

The avalanche method (highest APR first) always saves the most interest. That is the mathematical answer and it does not change. But for typical UK debts, where most credit cards sit in a similar 18 to 25% APR band, the gap is usually small, often only a few pounds a month.

The snowball method (smallest balance first) clears whole debts sooner, and those early wins are why people who start it are more likely to finish. Avalanche wins on paper. Snowball wins in real life.

This calculator runs both with your exact numbers, so you can see the gap for yourself before you choose. For a deeper comparison see our snowball vs avalanche guide.

How the calculator does the maths

TrySnowball runs a month-by-month simulation of your repayments. Each debt's APR is converted to a monthly rate, interest is added, minimum payments are applied, and any extra payment is routed to your focus debt. When a debt is cleared, its whole payment rolls into the next one. No rounding, no estimation.

Every debt-free date and interest figure on TrySnowball comes from this one simulation, so the calculator, the app, and your saved plan always agree.

Frequently Asked Questions

What is a debt snowball calculator?

A debt snowball calculator works out the order to pay off your debts using the snowball method (smallest balance first), shows your debt-free date, and calculates total interest. Enter each debt's balance, APR, and minimum payment, and the calculator handles the rest.

Is this calculator free?

Yes, completely free with no signup required. The calculator runs in your browser and doesn't store your data on our servers unless you create an account to track progress over time.

Does it work for UK credit cards, loans, and BNPL?

Yes. The calculator handles any UK debt with a balance, APR, and minimum payment - credit cards, personal loans, store cards, overdrafts, and BNPL agreements like Klarna or Clearpay. APRs are converted to UK monthly rates for accurate interest calculations.

How accurate is the debt-free date?

The calculator runs a full month-by-month simulation using your exact APRs and payments. The date is accurate to the month, assuming you make every payment on time and don't add new debt. Real life will vary - the calculator gives you a realistic target.

What's the difference between snowball and avalanche?

Snowball pays off the smallest balance first for psychological wins. Avalanche pays off the highest APR first to save the most interest. Avalanche saves more money on paper, but snowball has higher completion rates because the early wins keep you motivated. The calculator supports both.

Can I add extra payments?

Yes. The calculator has a slider for additional monthly payment on top of your minimums. Even £25 or £50 extra can shave months off your timeline and save hundreds in interest. Move the slider to see the impact instantly.

Worried your debts are unmanageable?

If your minimum payments alone are out of reach, free debt advice helps more than a calculator can. These UK charities offer free, confidential support:

No fees, no obligation. They'll explain your options including debt management plans, breathing space, and IVAs where appropriate.