Implied Probability Calculator
Convert decimal, American or fractional odds to implied probability instantly. Add the opposite-side odds for no-vig adjustment, and your true probability for an EV check. The single most-used tool in any sharp bettor's workflow.
What is implied probability?
Implied probability is the probability of a bet winning that the bookmaker's odds imply. It's the bookmaker's best estimate of true probability — plus the vig (their margin).
Decimal odds → implied probability
So 2.00 = 50%. 1.50 = 66.7%. 3.00 = 33.3%. Easy.
American odds → implied probability
So +150 = 40%. -200 = 66.7%. +100 = 50% (even money).
Fractional odds → implied probability
So 6/4 = 4/10 = 40%. 1/2 = 2/3 = 66.7%. Evens (1/1) = 50%.
What's the difference between implied and no-vig probability?
Implied probability includes the vig. Sum the implied probabilities for both sides of a 2-way market — it usually exceeds 100%. The excess is the bookmaker's overround.
No-vig probability strips that margin out. Each implied probability is divided by the total overround so they sum to exactly 100%. The result is the bookmaker's true estimate (not an inflation that pads their margin).
Use the no-vig version as your fair-price benchmark when comparing across books. The full breakdown: no-vig calculator.
How to use implied probability for value betting
Three steps:
- Calculate the implied probability of the bookmaker's odds.
- Calculate the no-vig probability (using opposite-side odds or a sharp benchmark).
- Compare to your true probability estimate. If yours > no-vig, the bet has positive expected value.
Without your own true-probability estimate (or a sharp model output), implied probability alone tells you nothing about edge. It's a benchmark, not a strategy.
Common implied-probability landmarks
| Decimal odds | American | Implied % | Real-world |
|---|---|---|---|
| 1.10 | -1000 | 90.9% | Heavy favourite — usually -EV at this price |
| 1.25 | -400 | 80.0% | Strong favourite |
| 1.50 | -200 | 66.7% | Solid favourite |
| 1.91 | -110 | 52.4% | Standard "vig-loaded coin flip" |
| 2.00 | +100 | 50.0% | True coin flip |
| 2.50 | +150 | 40.0% | Underdog |
| 3.50 | +250 | 28.6% | Long-shot |
| 5.00 | +400 | 20.0% | Outright contender, not favourite |
| 10.00 | +900 | 10.0% | Dark horse |
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What is implied probability in betting?
The probability the bookmaker's odds imply. Decimal odds: implied = 1/odds. It's their best estimate plus the vig.
How do I convert decimal odds to implied probability?
Implied probability = 1 / decimal_odds. So 2.00 = 50%, 1.50 = 66.7%, 3.00 = 33.3%. Multiply by 100 for percentage.
How do I convert American odds to implied probability?
Negative: implied = (-odds) / (-odds + 100). Positive: implied = 100 / (odds + 100). So -200 = 200/300 = 66.7%; +150 = 100/250 = 40%.
What's the difference between implied and no-vig probability?
Implied includes the vig (probabilities sum > 100%). No-vig strips it out (probabilities sum = 100%). No-vig is the fair-price benchmark.
How do I use implied probability to find value bets?
Compare your true probability estimate to the no-vig probability. If yours is higher, the bet has positive EV. Without your own estimate, implied probability alone is just a number.