About Smart Debt Calculator
Smart Debt Calculator exists to answer one question: how do I get out of debt faster and pay less interest?
Most credit card calculators show a single card. Real life isn't like that. Most households juggle two, three or four cards at different APRs and minimum payments. Our calculator simulates them all at once, month by month, so you can see your true picture.
How the maths works
- Interest accrues monthly at
APR / 12on each card's balance. - We pay every card's minimum first, then funnel any remaining budget into your target card.
- Avalanche targets the highest APR. Snowball targets the smallest balance. Minimums-only is the do-nothing baseline.
- When a card hits zero, its payment rolls into the next target — the “snowball” effect.
What we don't do
- We don't give financial advice.
- We don't store your data on a server. Saved plans live in your browser.
- We don't sell your details or take affiliate kickbacks from card issuers.
If you're struggling with debt, free help is available from StepChange, Citizens Advice and National Debtline.