How snowball and avalanche are calculated here
Both methods use the same debts, the same APRs, and the same extra payment. Minimums are paid on every balance. Snowball throws all extra dollars at the smallest balance first, then rolls that payment into the next-smallest. Avalanche throws extra at the highest APR first. We run both until the last balance hits zero and compare months and total interest.
Avalanche usually costs less interest. Snowball often feels faster because a small card vanishes first. If motivation is the bottleneck, snowball can still be the rational household choice — an unpaid plan that looks optimal on paper is worse than a plan you keep. The gap between methods shrinks when the extra payment is large relative to the balances.
This page assumes fixed APRs and no new charges. Issuers can reprice, add fees, or change minimums. If you have one card only, the credit-card payoff calculator is simpler. The strategy guide explains when a balance transfer is a third option — and when the transfer fee eats the teaser.
How to read your comparison
The headline number is the gap in total interest between snowball and avalanche — not a prize for finishing a single card. “Done in” months is when the last balance hits zero, not when the first account disappears. Snowball can still post an earlier first payoff because it hunts the smallest balance. Avalanche can finish on a similar calendar and still cost less interest if the APR gap is wide. Read both columns before you pick a label.
How to enter your debts
Copy the minimum from this month’s statement, not a round number you wish you were sending. In Extra, type only the surplus you can repeat every month after rent, food, and those minimums. If an issuer’s minimum shrinks as the balance falls, keep paying the old dollar amount anyway — that leftover becomes extra principal and usually shortens the timeline more than restarting from the new, smaller minimum.
A worked comparison
Try two debts: $2,400 at 27% APR with a $75 minimum, and $6,500 at 13% with a $140 minimum, plus $150 extra above those minimums. Note months to the first payoff, months to the last payoff, and total interest under each method. Then swap the balances (same APRs and minimums). Smallest-first and highest-APR-first no longer point at the same account, so the interest gap and the “quick win” gap show up as two different stories instead of the same card winning both races.
What this calculator does not model
Late fees, promotional APRs that expire, issuers that change the minimum formula mid-plan, income-driven student loan payments, collections or charge-offs, and new purchases are outside this comparison. Treat the two timelines as a planning sketch for balances you stop adding to, not a promise from your lender.