Debt Snowball Calculator

Enter each debt's balance, APR, and minimum payment, plus any extra you can put toward debt monthly. You'll see snowball and avalanche simulated side by side — debt-free date, total interest, and the payoff order for each — so you can pick the strategy you'll actually finish.

List each debt's balance, APR, and minimum payment. Leave unused rows blank — the name is optional but makes the payoff order easier to read.

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How the snowball vs avalanche comparison works

Both strategies use the exact same monthly budget: every debt gets its minimum payment, and everything extra goes to one target debt. They differ only in which debt gets targeted. Snowball attacks the smallest balance first — you kill a debt quickly, feel the win, and move on. Avalanche attacks the highest APR first — you starve the most expensive debt, which is mathematically optimal. The engine that makes either one work is the rollover: when a debt dies, its minimum payment doesn't go back into your pocket — it joins the extra and slams into the next target. That's why the payoff accelerates near the end even if you never raise your budget by a dime.

This calculator runs both strategies month by month on your actual debts and puts the results side by side: debt-free date, total interest, when your first debt disappears, and the full payoff order for each. Ties are broken sensibly — equal balances go to the higher APR first under snowball, equal APRs to the smaller balance first under avalanche.

The formula

monthly interest = balance × APR ÷ 1200    monthly budget = Σ minimums + extra (constant)

Balance is what you owe on one debt, APR its annual rate, and dividing by 1200 converts a percentage APR to a monthly decimal rate. Each simulated month: interest accrues on every living debt, every debt receives its minimum, and the remaining budget — extra plus every minimum freed by an already-dead debt — goes to the target. There's no closed-form formula for the finish line; the answer comes from running the plan, which is exactly what this calculator does, twice.

Worked example

Three debts: a $900 medical bill (0%, $50 min), a $4,200 credit card (22.9%, $105 min), and a $7,500 personal loan (11%, $210 min), with $200 extra — $565/month total against $12,600 of debt.

Snowball (medical bill → card → loan): first win at month 4, debt-free in 26 months, $2,072.55 interest.

Avalanche (card → loan → medical bill): first win at month 17, debt-free in 26 months, $1,914.90 interest.

Same debt-free date. Avalanche saves $157.65 — about $6 a month — while snowball hands you a victory 13 months sooner. That's the whole debate in one example: the math says avalanche, the psychology says snowball, and the gap is often small enough that either answer is right.

Psychology vs math — the honest answer

Avalanche always wins on interest, or ties. That's not an opinion; targeting the most expensive dollar of debt first is provably optimal, and this calculator will never show snowball costing less. But research on how people actually pay off debt — including work published in the Journal of Consumer Research and analyses by the Harvard Business Review — keeps finding the same thing: people who concentrate fire and score early, visible wins are more likely to stay with the plan. A payoff plan you abandon in month 7 has an interest cost of "forever," which beats any spreadsheet difference.

So use the numbers above, not a slogan. If your difference row shows avalanche saving $40, take the snowball's early win without guilt. If it shows $1,400, that's real money — and you can even split the difference: knock out one tiny balance first for momentum, then switch to avalanche order. The best strategy is the one that still has you making payments in month 20. One guardrail either way: if any debt's minimum doesn't cover its own monthly interest, the calculator flags it, because that balance grows until the rollover arrives — renegotiating that rate is more urgent than picking an order.

Frequently asked questions

Snowball or avalanche — which is better?

Avalanche (highest APR first) always wins on interest or ties — that's arithmetic, not opinion. But studies of real payoff behavior consistently find that the early wins of snowball (smallest balance first) keep more people on the plan, and a plan you quit costs more than any ordering difference. Run your own numbers above: if the difference row is small, pick by temperament; if it's large, lean avalanche.

What if I can't pay more than the minimums?

The strategies still work with $0 extra, just slower. Every time a debt is paid off, its minimum payment rolls into an attack on the next target instead of drifting back into your budget — that rollover alone accelerates the payoff toward the end. Even $25 of extra shortens the timeline more than most people expect, because it compounds through every rollover after it.

What is the debt rollover (the 'snowball effect')?

When a debt is eliminated, you keep paying the same total each month: the dead debt's minimum payment is redirected at the next target. Your total budget never changes, but the firepower aimed at a single debt keeps growing — like a snowball rolling downhill. Both snowball and avalanche rely on it; they only disagree about the order of targets.

Should I include my mortgage or student loans?

Usually no for the mortgage — its rate is typically far lower, the balance would dominate the plan, and most people treat housing as a separate goal. Low-rate federal student loans are a judgment call: include them if you want one unified debt-free date, exclude them if you'd rather concentrate on expensive consumer debt first. High-rate private loans belong on the list.

How much difference does the payoff order actually make?

Often less than people expect: with debts of similar rates, the gap can be a few dollars a month. It grows when your debts mix very high APRs with very low ones and the smallest balance happens to carry a low rate — then snowball parks money on cheap debt while expensive debt compounds. That's exactly what the difference row shows for your numbers, so you're deciding with facts instead of a rule of thumb.

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