What the snowball order actually costs

The choice between attacking the smallest balance and attacking the dearest rate is the most common question in a payoff plan, and it is usually answered with an opinion. For any given set of debts it has an arithmetic answer, so we computed it across a large synthetic corpus and published the corpus.

What the answer depends on is how far apart the rates are and how the balances are arranged, so the study reports the whole distribution rather than an average, and publishes the corpus it was computed from.

What the data shows

• The avalanche order was never the more expensive of the two: 10,000 of 10,000 portfolios, with 0 going the other way.
• The median extra interest under the snowball order was $190.41; the ninetieth percentile was $1,519.17, and the largest single difference measured was $8,414.15.
• In 33.06% of portfolios the snowball order cost under fifty dollars more, and in 52.97% both orders finished in the same month.
• In 64.02% of portfolios the snowball order cleared its first debt earlier, by a median of 1 yr — which is the thing it is chosen for.

1,018 points beyond $1,500.00 are counted here rather than drawn, so the axis is not stretched by the tail.

The dataset

Showing 12 of 10000 rows. The complete dataset — every row and every column — is in the CSV.

Download the full dataset (CSV) 10000 rows · 15 columns

The table shows the dataset's own rows, formatted as this site formats money and terms. The download carries the same rows unformatted, which is what a spreadsheet wants.

What was varied

Portfolios drawn

10,000

Debts per portfolio

2 to 5, drawn uniformly

Balance per debt

$300.00 to $25,000.00, drawn log-uniform

Rate per debt

no interest (0%), weight 1 · instalment-rate (4.5% to 11.99%), weight 2 · lower-rate card (12.99% to 18.99%), weight 3 · ordinary card (19.99% to 25.99%), weight 4 · high-rate card (26% to 29.99%), weight 2 — weights are relative, and are a modelling choice rather than a measurement of the market

Generator

mulberry32, seeded once per study and drawn in a fixed order: debt count, then for each debt its balance, its rate band, and — only when that band spans a range — its rate within it, then the extra-payment share. ⛔ The no-interest band is a single value, so it consumes no draw; a reader who always draws a rate will diverge from this corpus. Inserting or removing a draw anywhere changes every portfolio after it, which is why the order is part of the method and not an implementation detail.

Extra each month

5% to 60% of the portfolio's total minimums

Seed

20,260,917

What was held constant

Minimum payment (held constant)

Every debt's minimum is this month's interest plus 1% of the balance, with a $25.00 floor — a shape that always covers the interest, so every debt clears on its own minimum and the result is about the payoff ORDER rather than about the minimum. It is computed on the opening balance and held there for the term, which is the engine's model of a minimum payment. A flat percentage-of-balance minimum would not amortize above a certain rate and would make the ordering choice look far more expensive than it is.

Behaviour

Every payment lands on time, no new balance is added, no rate moves, no fee is charged and no promotional rate expires.

Plan anchor

January 2026 — pinned, so a rerun on any day produces identical output. These studies report terms and interest, never dates, so the anchor changes no published figure.

Data

Synthetic throughout. No customer data was used, approximated or fitted, and nothing here is a claim about what borrowers actually owe.

Engine version

payoff-25e86113b543

What was excluded, and how much

• 0 excluded — the payment does not clear the balance under one or both orders, so there is no pair of terms to compare.

How this was computed

Every portfolio was drawn from the distribution set out in the method block, then run through the payoff engine under each order in turn, with the same extra payment, the same minimums and the same plan anchor. Nothing else differed between the runs.

The engine is the code this site's calculators and the Dang! Payoff app run. It was not reimplemented for this study, and no figure on this page was computed anywhere else.

What the model assumes

Every payment lands on time, no new balance is added, no rate moves, no fee is charged and no promotional rate expires. The extra payment is constant, and the whole of it cascades to whichever debt the chosen order is attacking.

The minimum is computed on the opening balance and then held there for the whole term, because that is the engine's model of a minimum payment. A real minimum shrinks as the balance does, which lengthens a minimum-only payoff — the subject of a separate study here.

What this does not show

It does not show what American borrowers owe, or how common any portfolio in the corpus is. The corpus is drawn from a declared distribution, not observed in the world, and the distribution was chosen to span the shapes where a payoff comparison behaves differently — not to reproduce a population.

A median is also not a promise about your own debts. The spread is wide and the upper tail is long, which is why the distribution is charted rather than left as a single figure, and why the whole dataset is downloadable.

Synthetic data, and why

No customer data was used, approximated or fitted here. Our privacy posture does not permit research on customer balances without a separate review that has not happened, and a synthetic corpus is the honest alternative: it can be published in full, checked by anyone, and regenerated exactly.

Related

• When the cheaper order is barely cheaper
• Debt snowball vs avalanche
• Debt payoff calculator
• Methodology