Debt snowball vs avalanche: compare interest and payoff time
The snowball method targets the smallest balance first. The avalanche method targets the highest interest rate first. To compare them fairly, keep every balance, APR, minimum payment, extra payment, and total monthly budget identical, then change only the priority order.
Use the formula
- Monthly interest
- Current balance x APR / 12
- Monthly strategy budget
- Sum of original minimums + Extra payment
- Cost of choice
- Snowball total interest - Avalanche total interest
Worked example
The verified illustration uses five debts and a $150 monthly extra payment. It is an invented calculation scenario, not a real household and not a recommendation.
| Line | Result | Meaning |
|---|
| Starting debt | $27,500 | Five balances combined |
|---|
| Extra payment | $150 per month | Added to all original minimums |
|---|
| Snowball payoff | 40 months | Smallest balance first |
|---|
| Snowball interest | $8,229.67 | Month-by-month simulated total |
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| Avalanche payoff | 39 months | Highest APR first |
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| Avalanche interest | $7,587.76 | Month-by-month simulated total |
|---|
Repeatable method
- Collect current balances, APRs, and minimum payments.
- Choose one affordable extra payment used in both schedules.
- Check that every minimum covers current monthly interest.
- Simulate month by month with payment caps and rollover.
- Compare total interest, final month, and the payoff order before choosing.
Questions and answers
- Does avalanche always cost less?
- With standard positive-interest debts and the same payment budget, highest-rate-first is designed to reduce interest. Real products can contain promotional rates, fees, or changing terms that require a fuller model.
- Why might someone still use snowball?
- Some people value earlier account closures or motivation. That preference is separate from the interest calculation.
- What if a minimum does not cover interest?
- The balance may grow while waiting. Review the account terms and seek qualified help rather than trusting a payoff date from invalid inputs.
Sources
This is general educational arithmetic, not financial, credit, legal, or debt advice. Confirm statement terms and seek qualified help for repayment decisions.