Odds Converter & Calculator
Enter any odds format - decimal (1.85), american (-120), fractional (17/20), evens - and get the conversions, the implied probability and, for a full market, the book's margin: the silent price on every ticket. Recomputes as you type.
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What the margin means
The margin (a.k.a. the vig, juice or overround) is the gap between the implied probabilities summing to 100%. A fair 50/50 market would pay 2.00/2.00; at 1.85/2.05 the implied probabilities are 54.05% + 48.78% = 102.83%, so the book keeps roughly 2.76% of everything wagered. Esports moneylines we sampled run about 6-8% - lower than casual casino games, but it compounds every bet. Compare sampled margins per book in the comparison table →
Format cheat sheet
Decimal 1.85 pays 0.85 profit per 1 staked. American -120 means you risk 120 to win 100; +185 means you stake 100 to win 185 (and -110 is the standard "both sides" price). Fractional 17/20 pays 0.85 per 1. All three encode the same implied probability - the converter shows it. Fractional conversions are shown with their denominator capped at 100 and flagged when approximate.
Fair odds
For a full market the tool also computes the fair (no-margin) odds with the standard proportional method: each side's implied probability is scaled down so the sum is exactly 100%. If a book's 50/50 price pays 1.90 both sides, that is the fair coin-flip - anything lower is the margin you pay.