Debt repayment calculator

What this calculator does

It lines up your debts and simulates the two honest ways to clear them: smallest balance first (snowball) or highest interest first (avalanche), each with exactly the same money per month. You get the debt-free date, the total interest, and the payoff order for both, side by side. There is no trick to find here. The point is seeing what the ordering choice costs and what it buys, in your numbers rather than someone else's.

How this calculator works

How this calculator works: it simulates your debts month by month. Each month, every debt accrues one twelfth of its APR, every debt receives its minimum payment, and your extra amount goes to the target debt for your chosen order: smallest balance first (snowball) or highest APR first (avalanche). When a debt is cleared, its minimum payment is added to the extra amount from the following month onwards (the rollover that gives the snowball its name). Both orders are simulated with identical monthly outflow, so the only difference you see is the ordering itself.

Assumptions you should know about: interest accrues monthly (APR divided by 12), while many lenders accrue daily; payments land once a month on the same date; minimum payments stay fixed for the whole run, while many card issuers recalculate the minimum as a percentage of the balance each month; promotional rates (such as a 0% purchase window) are treated as permanent, so if your promo rate expires, edit the APR to the post-promo rate for the honest version; no fees, charges, or missed-payment penalties are modelled. The simulation stops at 100 years as an engineering limit, not a recommendation.

What the comparison honestly shows: at identical monthly outflow, avalanche never costs more in total interest than snowball; that is arithmetic, not opinion. Snowball clears your smallest balance sooner, and for some people the early win is what keeps the whole plan alive. Both results are on screen; pick the one you will actually stick to.

When to use it (and when not)

Use it when you hold more than one debt and have a spare amount to argue over; with a single debt every spare euro simply goes to it and there is nothing to order. Rerun it when a promotional rate expires or a minimum payment changes, because the answer can flip. If a balance is growing faster than you pay it, the tool will warn you; that situation needs your lender or a free debt advice service, not a chart.

This tool is educational, not financial advice and not debt advice. The results are arithmetic projections of the figures you enter, nothing more. They are illustrative: your lender's actual interest calculation may differ (daily rather than monthly accrual, fees, payment timing), so real payoff dates and interest totals will differ from these projections. This calculator makes no assumptions about typical interest rates or balances; every number on screen is one you typed or a placeholder example you should replace. Whether to prioritise debt repayment over other goals, such as an emergency fund or pension contributions, is a personal decision this tool does not make for you. If your debts feel unmanageable, or a minimum payment does not even cover the interest, speak to a free debt advice service in your country.