Snowball: smallest balance first
The snowball method directs any extra payment toward whichever debt has the smallest remaining balance, regardless of its interest rate, while you continue paying at least the minimum on everything else. Once that smallest debt is paid off, the amount you were putting toward it rolls into the next-smallest balance, and so on. The appeal is straightforward: individual debts get closed out sooner, which can be motivating to see on paper even before the larger balances are touched.
Because each payoff frees up the amount that account required, the total extra payment available for the next debt grows every time one is closed, which is where the method gets its name. The list of debts gets shorter fairly quickly at first, even if the total amount owed hasn't moved by much yet.
Avalanche: highest APR first
The avalanche method directs extra payment toward whichever debt has the highest interest rate, again regardless of its balance, while paying at least the minimum on the rest. The logic here is about cost rather than count: by targeting the debt that is accruing interest the fastest, you reduce the total amount of interest that accumulates across everything you owe before it's all paid off.
Under avalanche, the largest balance isn't necessarily first in line; a smaller balance with a much higher rate can take priority over a larger balance with a lower one. This can feel counterintuitive if you're used to thinking about debt size first, but it follows directly from the goal of minimizing what you pay in interest overall.
Why avalanche generally minimizes interest, with a caveat
When the monthly budget and the debts themselves are held constant, avalanche generally results in less total interest paid over the life of the payoff compared with snowball, because it targets the most expensive balance first. The size of that difference depends on how far apart your interest rates and balances actually are. If your rates are all similar, the two methods produce results that are close to each other; if one balance carries a much higher rate, the gap between the two approaches can be larger.
This is also where comparing the two approaches with your actual numbers is more informative than a general rule of thumb. The same two methods can produce a small gap for one household's debts and a meaningfully larger gap for another's, depending entirely on how the specific rates and balances line up.
Why snowball can still make sense for some people
Snowball trades some interest savings for faster, more visible wins: an account closed out completely, rather than a slowly shrinking rate-weighted total. For some people, that visible progress supports staying consistent with the plan for longer, which matters because a payoff strategy only works if it's actually followed through the full timeline, not just on paper.
There is no single answer for everyone
Neither method is universally better. Avalanche is generally the stronger choice if minimizing total interest is the main priority and you're confident you can stay consistent either way. Snowball can be a reasonable choice if the visible progress of closing accounts helps you keep going. The most useful step is comparing your own balances, rates, and monthly budget under both approaches side by side, rather than assuming one method is automatically right based on general reputation alone.
It's also worth remembering that both methods use the exact same total monthly budget; they only change the order debts are targeted in. Switching from one method to the other partway through doesn't undo prior progress, so if one approach stops working for you, moving to the other is a reasonable adjustment rather than a sign the plan has failed.