Debt payoff calculator: avalanche vs snowball
Enter each debt once. The calculator runs both payoff orders month by month against the same budget and shows what the difference actually costs you.
| Debt | Balance | Rate (APR %) | Minimum payment | Remove |
|---|
The extra is added on top of every minimum. As each debt clears, its payment rolls into the next one, so your total outlay stays the same until the last debt is gone.
This is an estimate, not advice. It assumes a fixed rate, a fixed payment and no new borrowing, fees or late charges. Real cards have variable rates and minimums that shrink as the balance falls, which stretches payoff further than the figures here. Use it to compare the two orderings, not to predict an exact date.
What the two methods actually do
Both methods pay every minimum every month. The only thing that changes is where the spare money goes. The avalanche puts it on the debt with the highest interest rate. The snowball puts it on the debt with the smallest balance. Everything else — your total monthly outlay, the minimums, the rolling of freed-up payments into the next debt — is identical.
That single difference is why the avalanche always wins on arithmetic. Interest is charged on balances, so attacking the most expensive rate first removes the fastest-growing part of the debt first. The calculator above will never show the snowball costing less, unless your smallest balance happens to also be your highest rate, in which case both methods pay the same debts in the same order and finish level.
When the difference is worth caring about
Run your own numbers before assuming the gap matters. With the sample figures loaded above, the avalanche saves a few hundred dollars over roughly two and a half years. On a debt load where the rates are close together, the gap can come out near zero — and a method you will actually stick with for thirty months beats a marginally cheaper one you abandon in month four.
The gap widens when your rates are far apart, and it widens most when your smallest balance carries your lowest rate. That is the case where the snowball spends months clearing something cheap while an expensive balance keeps compounding. If the calculator shows a large saving, that is usually the shape of your debts.
What this calculator does not model
It assumes a fixed rate, a fixed minimum payment and no new borrowing. Real credit cards break all three. Most card rates are variable and move with the prime rate. Most card minimums are a percentage of the balance, so they shrink as you pay down — which stretches payoff considerably if you only ever pay the minimum. The calculator holds your minimum constant, which is closer to what actually happens once you commit to a fixed payment, but it is still a simplification.
It also ignores fees, late charges, promotional rates that expire, and balance transfers. If you are carrying a 0% promotional balance, note the date it ends — the rate that follows is usually the thing that determines your payoff order, not the balance today.
Before you pick an order
Two things generally come before optimising the payoff sequence. The first is making sure the minimums are covered every month without fail, because a missed payment costs more in fees and credit damage than any ordering strategy saves. The second is holding a small cash buffer, so that an unexpected bill does not go straight back onto the card you are trying to clear. Our emergency fund calculator will size that buffer against your own essential costs.
If the spare money in the calculator above is smaller than you would like, the constraint is usually the budget rather than the debt. The 50/30/20 budget calculator shows where your take-home pay is currently going, and how to create a personal budget covers the mechanics in more detail. If you are weighing a consolidation loan against paying the cards directly, personal loans explained sets out what to check before borrowing.
