There is no argument about which order costs less. Highest interest rate first, the avalanche, always wins on arithmetic. The argument is about whether the difference is large enough to matter, and that is a question with a number attached to your own debts rather than an opinion.
Both Methods Share the Same Engine
The part people skip past is the part that does the work, and it is identical in both methods:
- Every debt gets its required minimum payment, every month, without exception.
- Whatever you can pay above the total of those minimums goes entirely to one target debt.
- When that debt clears, its payment is added to the next target rather than absorbed back into spending.
Step three is the whole thing. The total you pay each month never falls until the last debt is gone, so the amount attacking the remaining balance grows every time an account closes. That is where the acceleration comes from, and it happens whichever order you choose. Somebody who lets the freed up payment quietly become spending money is not running either method.
What Separates Them
| Avalanche | Snowball | |
|---|---|---|
| Target order | Highest interest rate first | Smallest balance first |
| Total interest | The lowest possible | Higher, by definition |
| Time to clear everything | Shortest | Longer |
| First account closed | Later, usually | Sooner, usually |
| The argument for it | It costs less | More people finish it |
The size of the gap depends on how far apart the rates are and how far apart the balances are. Where every debt is a credit card at roughly the same rate, the two orders produce nearly the same answer and the choice does not matter. Where one debt is a card at 21.99% and another is a student loan or a secured line in single digits, the avalanche wins clearly, and paying the small cheap debt first is expensive.
The Rates You Are Actually Choosing Between
The order only matters because the rates differ, so it is worth seeing the real spread. Across the 98 personal credit cards we track:
- The most common purchase rate is 21.99%, on 55 of the 94 cards that publish one. Another 19 charge 20.99% and 9 charge 19.99%.
- The lowest published purchase rate is 8.90%, and low rate cards generally trade the rate for an annual fee.
- Cash advances are charged separately and higher. The most common cash advance rate is 22.99%, on 61 cards, and the highest we record is 24.99%. Cash advances also get no interest free period at all, so they start accruing the day they are taken.
- Four cards publish no purchase rate, because the issuer prices against prime rather than publishing a number. We leave those blank rather than converting a formula into today’s arithmetic.
A line of credit sits well below all of this. Priced at prime plus a spread, with prime at 4.45% as of 20 August 2026, an unsecured personal line in the high single digits is roughly a third of the cost of carrying the same balance on a card. That ordering is what the avalanche is exploiting.
Why the Snowball Survives an Argument It Loses
The case for the snowball is behavioural and it is not silly. Clearing a whole account in six weeks is visible in a way that lowering a large balance by 4% is not, and a plan somebody abandons in month four costs more than a slightly worse plan they finish. Debt repayment is not a maths problem being solved once, it is a maths problem being sustained for two or three years.
That said, the honest version of the argument requires knowing the price. Someone who says they will take the snowball because the difference is small should have seen the difference. Sometimes it is $80, in which case take the one you will finish. Sometimes it is $1,900 and eleven months, in which case it is worth trying harder to stay with the cheaper order.
There is also a middle option that gets ignored. Clear one small balance first for the momentum, then switch to strict highest rate order. That captures most of the behavioural benefit and most of the savings, and nothing about either method forbids it.
Four Things That Change the Answer Entirely
- A promotional rate that is about to end. A balance sitting at 0% until March is not a low interest debt, it is a high interest debt with a delay on it. Order the payoff against the rate that will apply, not the one showing today.
- Anything in collections or about to default. That comes first regardless of rate. The cost of an account going bad is not an interest rate.
- An employer pension or group RRSP match. The matched portion is an immediate return on contribution, which is normally larger than any interest rate you are paying. Most people treat capturing the full match as prior to the debt plan.
- Having no cash buffer at all. Paying every spare dollar at debt with nothing set aside means the next unexpected bill goes straight back onto the card at 21.99%, which undoes the progress and the morale at once.
That last one is the most common way a good plan fails. This is a description of how the trade-off is usually framed rather than advice about your situation, and none of it accounts for anything specific to you.
Run It Rather Than Argue About It
The debt payoff calculator takes your actual balances, rates and minimum payments and runs both orders side by side, so the choice is made against a real difference in dollars and months. Everything happens in the browser and nothing you enter is stored or sent anywhere.
If most of the balance is on one card, the credit card payoff calculator is the simpler tool, and it works interest daily the way a statement does. If a promotional transfer is on the table, price it first, because the transfer fee is real money and the promotion has an end date.
The Benchmark Weekly
One email a week. Elevated welcome offers while they are still open, new cards and accounts as they arrive, and any fee, rate or earn rate that moved, with the old figure and the new one. A quiet week gets no email.