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With Elo ratings, the side rated D points higher wins with probability 1 / (1 + 10−D/400). Equal ratings give 50%, a 100-point edge gives 64%, 200 points 76% and 400 points 91%. Backwards, a 70¢ favourite on Polymarket is priced like a 147-point Elo edge.
Uses the standard 400-point scale. Where draws are possible (chess, soccer) the result is the expected score — a win counts 1 and a draw ½ — not the chance of an outright win.
Read backwards, the formula turns a price into a rating gap. The most traded upcoming two-way games on Polymarket, October 5, 2026:
| Game | Favourite | Chance | Elo gap |
|---|---|---|---|
| Falcons vs. Saints NFL | Saints | 53.5% | 24 |
| Counter-Strike: Spirit vs MOUZ (BO3) - ESL Pro League Group Stage Esports | Spirit | 63.5% | 96 |
| Counter-Strike: M80 vs TYLOO (BO3) - ESL Pro League Group Stage Esports | TYLOO | 51.5% | 10 |
| China Open: Coco Gauff vs Xinran Sun Tennis | Coco Gauff | 90.5% | 392 |
| Counter-Strike: Vitality vs Team Falcons (BO3) - ESL Pro League Group Stage Esports | Vitality | 63.5% | 96 |
| Counter-Strike: Aurora Gaming vs BetBoom Team (BO3) - ESL Pro League Group Stage Esports | Aurora Gaming | 63.5% | 96 |
| LoL: Maryville University vs Zeu5 Esports (BO5) - LCS Promotion Playoffs Esports | Maryville University | 91.5% | 413 |
| Ravens vs. Falcons NFL | Ravens | 64.5% | 104 |
| Cowboys vs. Eagles NFL | Eagles | 66.5% | 119 |
| Bills vs. Rams NFL | Rams | 59.0% | 63 |
| LoL: KaBuM! Ilha das Lendas vs 9z Globant (BO5) - CBLOL Promotion Playoffs Esports | KaBuM! Ilha das Lendas | 86.5% | 323 |
| 49ers vs. Seahawks NFL | Seahawks | 59.0% | 63 |
Chance = the favourite's price divided by the sum of both prices, so the small gap between them is removed. All games and prices: Polymarket game odds by league, refreshed twice a day. Soccer is left out because draws break the two-way formula.
Elo gives every team or player a rating and turns the difference into an expected result on a logistic curve: every 400 points multiplies the odds by 10. Near an even matchup each 10 Elo points is worth about 1.4 percentage points; far from even the same gap moves the probability less. Home advantage is added to the home side's rating before the formula, and its size depends on the rating system you use. Polymarket prices work the other way round: they are the probability itself, so the calculator turns them back into the rating gap that would produce them — see how sports game markets work, the moneyline in the glossary, or compare a sportsbook line with the odds converter.
Put real prices into the calculator: every page below shows current odds, 24-hour moves and the market rules.
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Most traded right now:
Use 1 / (1 + 10^(−D/400)), where D is the rating difference. A 100-point edge is about 64%, 200 points about 76% and 400 points about 91%.
Use D = 400 × log10(p / (1 − p)). A 70% favourite corresponds to about 147 Elo points, a 60% favourite to about 70.
Add the home advantage to the home side's rating before converting. In games that can end in a draw, the Elo formula gives the expected score (a draw counts as half a win), not the chance of winning outright.
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