How this calculator works
When you carry several debts, the order you attack them in changes how much interest you pay and how long you stay in debt — sometimes by years. This tool simulates your payoff month by month: every debt accrues interest, you pay every minimum, and your extra payment is hurled at one target debt until it's gone, at which point its payment rolls onto the next. That rolling, compounding effect is why a focused plan beats spreading extra money thinly across everything.
Two strategies decide the target. The avalanche attacks the highest interest rate first — mathematically optimal, it always pays the least total interest. The snowball attacks the smallest balance first — it costs a little more, but clearing a whole debt early delivers a motivating win that keeps many people going. This calculator runs both so you can see the real trade-off in dollars and months for your exact debts.
The method
Each month, every debt accrues interest at its monthly rate, then payments are applied:
The simulation repeats until every balance is zero, recording your debt-free date, total interest, and the month each debt is cleared.
- Store Card $2,000 @ 9%, Credit Card $11,000 @ 25%, Medical $5,000 @ 0%.
- Snowball (smallest first) clears them in about
36 monthswith$5,900interest. - Avalanche (highest rate first) clears them in about
30 monthswith$3,100interest. - Same money, same debts — avalanche saves roughly
$2,800and six months.
Acronyms used on this page
- APR
- Annual Percentage Rate
Why extra payments matter so much
Minimum payments are designed to keep you in debt — a large share goes to interest, barely denting the balance. Every extra dollar, by contrast, goes entirely to principal, which removes all the future interest that dollar would have generated. That's why adding even $100 a month often cuts years off the timeline. Drag the extra-payment slider and watch the debt-free date jump.
Frequently asked questions
Is snowball or avalanche better?
Avalanche (highest rate first) always costs the least interest and usually finishes fastest. Snowball (smallest balance first) costs a bit more but gives faster early wins that help many people stick with it. This tool shows both differences for your debts.
How does the snowball work?
Pay every minimum, throw all extra at the smallest balance, and when it's gone, roll its payment into the next-smallest. The freed-up payments snowball, speeding up each payoff.
Should I save or pay off debt first?
Most guidance: keep a small starter emergency fund, then attack high-interest debt aggressively, since few investments reliably beat a 20%+ interest rate. This tool focuses on the payoff side of that plan.
Does this account for new charges?
No — it assumes you stop adding to these balances. New charges restart the interest clock, so pausing the cards while you pay them down is part of any plan working.