Convert between American, decimal, fractional odds and implied probability. Type into any field — all the others update instantly.
Enter both sides of a two-way sportsbook market to get the no-vig fair probability and the bookmaker's margin.
| American | Decimal | Fractional | Implied % |
|---|---|---|---|
Tap any row to load those odds into the converter above.
Odds formats describe the same price in different ways. The implied probability includes the sportsbook's margin; use the vig remover above when you need a two-way no-vig estimate.
For positive odds, probability = 100 / (odds + 100). For negative odds, probability = |odds| / (|odds| + 100). For example, +150 converts to 40.0%, while -110 converts to 52.38% before removing vig.
Probability = 1 / decimal odds. Decimal odds of 2.20 therefore imply 45.45%. A $10 stake at 2.20 returns $22 in total when it wins: $12 profit plus the $10 stake.
For fractional odds A/B, probability = B / (A + B). Odds of 3/2 imply 40.0% and are equivalent to +150 American or 2.50 decimal.
At -110, you stake $110 to make $100 profit. The price implies a 52.38% probability before accounting for the bookmaker's margin.
For positive American odds, use 1 + odds / 100. For negative odds, use 1 + 100 / |odds|. That makes +150 equal to 2.50 and -110 approximately 1.91.
For decimal odds of 2.00 or higher, use (decimal - 1) × 100. Below 2.00, use -100 / (decimal - 1). Round only the displayed American price, not intermediate calculations.
No. Implied probability is the probability encoded by the quoted price and normally includes vig. Fair probability is an estimate after removing the margin or applying an independent model.
It converts both sides to implied probabilities, adds them to measure the overround, then divides each side by that total. The normalized probabilities sum to 100%.
On Polymarket the price is the probability. If a contract trades at 60¢ the market is saying the probability is 60% — no vig, no format conversion. Buy at 60¢, contract pays $1 if it resolves YES.
ZenHodl publishes calibrated win-probability models for 8 public API sports. See our fair-value calculator or read the full odds formats explainer.
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