How this calculator works
Each month it adds interest at your APR (divided by twelve), subtracts your payment, and repeats until the balance hits zero — the same amortisation your lender runs. The extra-payment scenario reruns the schedule with your payment plus the extra, and shows the interest and months you save.
If your payment doesn't even cover the monthly interest, the calculator says so instead of pretending. That situation is exactly the minimum-payment trap the US CFPB warns about: pay only the minimum on a high-rate card and it can take years, because most of each payment feeds the interest rather than the balance.
Common questions
Where do I find my APR?
On your statement or in your banking app, usually labelled APR or annual interest rate. Credit cards commonly sit above 20%; personal loans and car loans are typically lower. If you see a monthly rate, multiply by twelve for a close-enough APR.
Why does a small extra payment make such a big difference?
Because every extra unit goes straight at the balance, and a smaller balance accrues less interest every month after — the saving compounds. On high-APR debt, modest extras routinely cut years off the schedule.
Should I pay off debt or invest?
For high-interest debt, paying it down is usually the better move: clearing a 22% card is a guaranteed 22% return, which investments can't reliably match. Once high-rate debt is gone, long-term investing generally takes over as the priority.
Does this work for any kind of debt?
It models any fixed-rate debt repaid monthly — credit cards, personal loans, car finance. It doesn't model variable rates, fees, or promotional 0% periods ending; treat those as reasons your real schedule could differ.
This tool is educational and not financial advice. If debt is overwhelming, free debt-advice services exist in most countries — reaching one early is a strength, not a failure.
- 1.Minimum payments and how long debt takes to clear — US Consumer Financial Protection Bureau, 2024
- 2.How to reduce the cost of your credit and store card debt — MoneyHelper (UK)