How the debt snowball works
You keep paying the minimum on every debt so nothing goes delinquent, then throw every spare dollar at the debt with the smallest balance. The moment it clears, its minimum payment joins your extra payment and both attack the next-smallest balance. Each payoff makes the next one faster, which is where the snowball name comes from.
The mechanism that actually saves money is the rolled-up payment, not the ordering. By the final debt you may be paying several hundred dollars a month more than you started with, without any change to your budget.
Snowball versus avalanche
The avalanche method targets the highest interest rate first and mathematically always costs the same or less. In realistic consumer debt mixes the gap is often a few hundred dollars and a month or two — small enough that the behavioural advantage of quick wins can be worth more than the interest difference.
The comparison panel above prices that trade-off with your own numbers, so you can decide with the actual figure rather than a rule of thumb. If the difference turns out to be large, run the debt avalanche calculator and take the cheaper route.
Getting your numbers right
Use current balances from your latest statements, the purchase APR for each card, and the actual minimum payment your creditor requires. Credit card minimums shrink as the balance falls; this calculator holds them fixed, which is conservative in your favour and matches how most people actually pay.
Keep a small emergency buffer before you commit every spare dollar. A surprise expense charged back onto a card undoes months of snowball progress.
Common mistakes
Continuing to use the cards you are paying down, skipping the buffer, and stopping the rolled-up payment after the first debt clears. The last one is the most costly — the freed payment has to keep moving down the list for the snowball to work at all.