Debt Avalanche Calculator
Plan a highest-interest-first debt payoff strategy. Enter your debts and monthly payment budget to see which debt to target first, when you could become debt-free and how much interest you may avoid.
Based on payments starting in January 2026 and a monthly debt-payment budget of £650.00.
Do this next
Pay the required minimum on every debt, then put your initial extra payment of £350.00 toward Store card first. Its APR is 34.9%.
Your payoff order
The order is based on the highest APR among your remaining debts. You still make the required minimum payment on every open debt.
- Target 1Store card
- Target 2Credit card
- Target 3Personal loan
The comparison assumes you keep making only the fixed minimum payments entered and do not roll freed payments to other debts.
| Metric | Debt avalanche | Minimum payments only | Difference |
|---|---|---|---|
| Debt-free date | April 2027 | January 2032 | 4 years, 9 months sooner |
| Time to repay | 1 year, 4 months | 6 years, 1 month | 57 months |
| Total paid | £10,269 | £14,387 | £4,118 |
| Total interest | £1,069 | £5,187 | £4,118 |
Minimum payments only uses the fixed minimum payments you entered. It does not include your planned extra payment or roll cleared payments to other debts.
This schedule is an illustration using monthly interest and fixed minimum payments. Your lender’s actual balance may differ.
| Debt | Starting balance | Estimated payoff |
|---|---|---|
| Store card | £1,200 | April 2026 |
| Credit card | £3,000 | October 2026 |
| Personal loan | £5,000 | April 2027 |
How the debt avalanche method works
The debt avalanche method targets the debt with the highest interest rate first. You continue making the required minimum payment on every debt, then put all remaining money toward the highest-APR debt. When it is cleared, you roll that payment into the next debt in the order.
Because high-rate borrowing stops accumulating interest sooner, this approach generally minimises estimated interest when the same monthly payment budget is used consistently.
- Make the required minimum payment on every open debt.
- Use all remaining budget as an extra payment on the open debt with the highest APR.
- When that debt is paid off, roll the freed payment into the next-highest APR debt.
- Continue until every debt is cleared.
How to use this calculator
- Pick your currency at the top of the calculator. It changes formatting only, not the maths.
- Enter the total amount you can pay toward all debts each month. Include every minimum payment plus any extra you can afford.
- Add each debt with its name, current balance, interest rate (APR) and required minimum monthly payment. Use Add another debt for more, up to 20.
- Read the payoff order, estimated debt-free date and the comparison against paying only the minimums you entered.
Results update as you type. The plan assumes payments start in the current month, which is stated above the results.
How this calculator works
This calculator uses a monthly repayment model. It converts each annual percentage rate (APR) into a monthly rate by dividing it by 12, adds estimated interest to each outstanding balance, then applies the payments you entered.
- APR — the annual percentage rate you enter for a debt (24% → a 2% monthly rate)
- Each month: add the interest, pay every minimum, then spend what is left on the highest-APR debt
- When a debt clears, its freed payment rolls into the next debt the same month
- For equal APRs, the larger balance is targeted first, then the order debts were entered
For example, an APR of 24% is modelled as a monthly rate of 2% (24% ÷ 12). With the example debts — a £3,000 card at 29.9%, a £1,200 store card at 34.9% and a £5,000 loan at 9.9% — and a £650 monthly budget, the £300 of minimums are paid first and the remaining £350 goes to the store card, because it has the highest APR.
What does this calculator assume?
- Interest is modelled monthly and is added before the payment is applied.
- You keep making the fixed minimum payment entered on every open debt.
- Any remaining monthly budget is directed to the open debt with the highest APR.
- When a debt is cleared, unused payment money is immediately directed to the next debt in the order.
- For equal APRs, the calculator targets the larger balance first, then uses the order debts were entered.
- The minimum-payments-only comparison keeps the fixed minimums entered and does not roll payments forward.
- Actual lender interest may be calculated daily and can be affected by statement dates, fees, changing minimum payments, promotional offers, missed payments, charges and settlement terms.
- The calculator does not model fees, penalty charges, early repayment charges, interest-rate changes, payment holidays, lender-specific minimum-payment formulas or settlement offers.
How does the minimum-payments-only comparison work?
The comparison runs a second, separate plan in which you pay each debt’s entered minimum every month and nothing more — no extra payment, and no rolling a cleared debt’s payment into another. It uses the same monthly interest timing and the same 100-year safety limit. The interest and time differences shown are only displayed when both plans clear every debt inside that limit.
Important information
Important: This calculator is an educational planning tool, not financial or debt advice. It cannot reproduce a lender’s exact statement balance, daily interest, fees or contractual payment rules, and the payoff date and interest figures are estimates based on the figures you enter.
Use it for planning repayments on non-priority debts such as credit cards, overdrafts, store cards and personal loans. If you are behind on rent or mortgage payments, council tax, energy bills, court fines or other essential bills, deal with those first. If you are struggling to pay, contact your creditors as soon as possible. Free, confidential debt advice may be available from StepChange, National Debtline and Citizens Advice.