Avalanche pays the highest interest rate first and costs you the least money. Snowball pays the smallest balance first and gives you a win sooner. Avalanche is mathematically better and snowball is behaviourally better, and the gap between them is usually smaller than people assume.
The variable that actually decides how fast the debt clears is how much you put toward it each month, not which order you pick.
Avalanche, always, because it kills the most expensive interest first. On typical consumer debt the difference over the life of the payoff is often a few hundred dollars and a month or two, which is why snowball still wins for people who need to see progress to keep going.
Compare the interest rate to the return you would expect after tax. Credit card debt in the high teens or twenties beats any realistic market return, so it goes first. A mortgage in the low single digits usually does not. Employer match on a 401k comes before either, because it is an immediate return.
Paying down revolving balances helps by lowering utilisation. Closing the account afterwards can hurt, because it reduces total available credit and eventually shortens your average account age. Pay it off and leave it open.
Only if the new rate is genuinely lower after fees, and only if the behaviour that created the balance has changed. Consolidation moves debt rather than reducing it, and a cleared credit card with an unchanged budget tends to refill.
Debt payoff calculator
Enter your balance, rate and monthly payment. See how long it takes, how much interest you hand over, and exactly what paying more would save.
Start from
Paying $250/mo, you'll be debt-free in
6 years and 10 months
82 payments in total
Interest paid
$10,319
Total you pay
$20,319
You borrowed $10,000 and you'll hand back $20,319 — that's $10,319 of pure interest, or 103% on top of what you actually owe. The first month alone, $200 of your $250 payment goes straight to the lender.
Same balance, same rate — only the monthly payment changes. Your payment is highlighted.
| Monthly | Payoff time | Interest | Total paid | You save |
|---|---|---|---|---|
| $250you now | 6y 10m | $10,319 | $20,319 | — |
| $300 | 4y 8m | $6,644 | $16,644 | $3,6752y 2m sooner |
| $400 | 3y | $4,001 | $14,001 | $6,3183y 10m sooner |
| $500 | 2y 2m | $2,899 | $12,899 | $7,4204y 8m sooner |
| $750 | 1y 4m | $1,748 | $11,748 | $8,5715y 6m sooner |
| $1,000 | 1y | $1,270 | $11,270 | $9,0495y 10m sooner |
$750 more a month — $1,000 instead of $250 — clears it in 12 months instead of 6 years and 10 months, and saves you $9,049 in interest.
Interest is charged monthly on whatever balance is left, at your APR divided by 12. Each payment covers that month's interest first; only the leftover reduces the balance — which is why a payment barely above the interest charge takes decades. We run the payoff month by month, so the final (partial) payment is counted exactly rather than rounded up to a full one.
The model assumes a fixed rate, a fixed payment every month, and no new spending on the card. Real credit-card minimum payments are a percentage of the balance, so they shrink as the balance falls — that stretches the payoff even longer than a flat minimum would. Fees, promotional rates, variable APR changes and interest-charge rounding by your lender aren't modelled. If the payment doesn't exceed the monthly interest charge, the balance never falls and the debt never clears.
This is an estimate for planning, not financial advice. Your numbers never leave your browser — nothing you type here is stored, sent, or tracked. Want your real balances and payments tracked automatically? That's what Deco is for.