ATROPOSThe survivor pool calculator: four numbers that matter
A useful survivor calculator produces four numbers: true win probability, season survival odds, ownership-adjusted pick value, and the split. Most tools stop after the first. The last two are where the money is.
1 · Devigged win probability
Moneylines carry the book's margin. Convert both sides to implied probability and normalize: -350/+280 devigs to about 74.7% / 25.3%. Four points of vig on a "lock" compounds brutally across 20+ picks. Atropos's board shows devigged probabilities for every team every week, with measured drift bands for future weeks (one week out, lines move about a point; twelve weeks out, ±13).
2 · Season survival odds
Weekly probabilities multiply. 0.7524 ≈ 0.1%; 0.8024 ≈ 0.5%. Even a perfect route of heavy favorites dies in most seasons — which is why half of large-contest seasons end with nobody left, and why the wipeout ending is a payout channel, not an edge case.
3 · Ownership-adjusted pick value
The number no simple calculator produces, because it requires a model of everyone else. The same 80% favorite is a different asset at 20% ownership than at 80% ownership: surviving with the herd means splitting with the herd. Atropos projects ownership from measured field behavior across millions of Monte Carlo season simulations and prices every cell of the board with it.
4 · The split
Prize ÷ co-survivors, or prize ÷ the final cohort under the wipeout rule. The measured consequence in a simulated $21M contest: the safest-looking strategy returned 0.36x (alive, but 47 deep in company) while leverage routes returned 1.76x — split-adjusted EV is the objective the other three numbers feed.
FAQ
How do I calculate my survivor pool odds?
Multiply your weekly win probabilities. Picking 75% favorites for 24 picks compounds to about 0.1% (0.75^24); picking 80% favorites compounds to about 0.5%. That is the whole game in one line: tiny weekly edges compound enormously, and no route of favorites is remotely safe over a full season.
How do you remove the vig from a moneyline?
Convert both sides to implied probability (for -350: 350/450 = 77.8%; for +280: 100/380 = 26.3%), then divide each by their sum (104.1%). The -350 favorite devigs to roughly 74.7%. Devigged moneylines are the best public estimate of NFL win probability — a -350 'lock' loses one time in four over a season of such picks.
How do you calculate a survivor pick's value?
Win probability times what surviving is worth — and what surviving is worth depends on ownership. If 50% of the field is on your team and it wins, you gained almost no separation; if it loses, half the pool's equity transfers to everyone else at once. Pick value = P(win) x expected prize share given who survives with you, which requires an ownership projection, not just a moneyline.
How is a survivor pool prize split calculated?
Prize divided by co-survivors — or, in roughly half of large-contest seasons, divided among the final elimination cohort under the wipeout rule. In 1,000,000 simulations of a $21M contest, the chalk route finished with ~47 co-survivors: $21M split 47 ways is the difference between the headline number and the 0.36x measured return.
What are the odds of winning a survivor pool outright?
In large contests, solo survival is rare enough that most equity flows through splits and wipeout endings. 53.6% of simulated seasons of the 2026 Splash World Championship end with the entire field eliminated, and 12.7% end before week 15 even plays — a calculator that only prices the sole-survivor ending misprices most of the prize pool.
What an optimizer should optimize → · How to make picks · Glossary