Implied Probability
Implied Probability Calculator: The Win Probability Behind the Odds
Implied probability is the win probability built into a price: +100 (2.00) is 50%, -200 (1.50) is 66.7%, and the formula for decimal odds is 1 ÷ odds. The implied probability calculator converts two or three sides of a market into probabilities; the amount by which they add up to more than 100% is the sportsbook's vig, and removing it proportionally gives the market's true estimate. Compare that with your own number: the side you rate higher than the market is the side with value.
Implied Probability Calculator
Implied ProbabilityConvert odds into the market's win probability and find the side with value
Implied probability = 1 ÷ decimal odds; no-vig probability = implied probability ÷ Σ(implied probabilities of all sides)Σ is the sum of every side's implied probability, typically between 1.03 and 1.10.
How to use the implied probability calculator
Enter both sides of the same market from your sportsbook as A and B, converting American odds to decimal with the Odds Converter; for a soccer 3-way moneyline, put the draw in the third field. The calculator computes the implied probabilities with vig, adds them up, then removes the vig proportionally to show the market's true estimate of each side.
Implied probabilities with vig always sum to more than 100%. That is not an error; the excess is the sportsbook's margin. A market at -111 (1.90) and -118 (1.85) sums to 106.7%, a 6.7% vig; strip it out and side A is 49.3%, side B 50.7%. For comparison, standard -110 (1.91) on both sides is 52.38% each, 104.76% in total.
The no-vig probability is the number to measure yourself against. If you rate the Chiefs to cover at 55% and the market's no-vig estimate is 49.3%, that 5.7-point gap is your value; confirm it with the expected value calculator and size it with the Kelly criterion.
Reading line movement with implied probability
Recalculating implied probability as a line moves shows which way the market is leaning. If a favorite goes from -105 (1.95) to -125 (1.80), its implied probability rises from 51.3% to 55.6%: the market, or the sharp money, has moved toward the favorite, and your original 55% estimate no longer carries an edge.
Because most states have several legal sportsbooks, the same market is often priced differently across books. Run the calculator on each book's price and bet the side where the implied probability is lowest, which is the best price for your side.
Example: Chiefs -3.5 at -111 (1.90), Bills +3.5 at -118 (1.85)
- Implied probability A = 1 ÷ 1.90 = 52.6%; B = 1 ÷ 1.85 = 54.1%; total 106.7%, vig 6.7%.
- No-vig: A = 52.6 ÷ 106.7 = 49.3%; B = 54.1 ÷ 106.7 = 50.7%.
- The market rates the two sides close to a coin flip, with the Bills slightly favored to cover.
If you rate the Chiefs to cover at 55%, that is 5.7 points above the market's no-vig 49.3%, so there is value on the Chiefs. But the break-even rate at -111 (1.90) is 52.6%, only 2.4 points below your estimate, for an EV of about +4.5%; the edge is real but modest, so keep the stake small.
FAQ
How do you calculate implied probability?+
For decimal odds, implied probability = 1 ÷ odds: -111 (1.90) is 52.6%, +150 (2.50) is 40%, -400 (1.25) is 80%. For American odds use 100 ÷ (odds + 100) on plus prices and odds ÷ (odds + 100) on minus prices, ignoring the sign.
Why do the implied probabilities add up to more than 100%?+
The excess is the sportsbook's vig. At -111 (1.90) and -118 (1.85) the two sides total 106.7%, a 6.7% vig; at standard -110 on both sides the total is 104.76%. Only after removing the vig do you get the market's true estimate.
Is implied probability the same as true probability?+
No. Implied probability includes vig and reflects the market's collective opinion, not the real chance of the outcome. The no-vig figure is closer to what the market believes, but it can still be wrong, and that gap is where value betting lives.
How do you convert American odds to implied probability?+
Plus odds: 100 ÷ (odds + 100). Minus odds: odds ÷ (odds + 100), using the number without the sign. So +150 is 40% and -110 is 52.4%. You can also convert to decimal odds first with the Odds Converter and use 1 ÷ odds.
How do you calculate implied probability on a 3-way market?+
Take 1 ÷ odds for each of the three outcomes, add the three numbers to get the total, then divide each by the total to remove the vig. Soccer 3-way moneylines usually carry a higher vig than two-way markets such as spreads and totals.
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A calculator answers the formula; the AI answers the game. Mysports.AI compares model win probability against market odds every day and flags the prices that look mispriced.
For informational purposes only. Sports betting is legal in 39 states and D.C.; rules and minimum age vary by state. 21+. Gambling problem? Call 1-800-GAMBLER.
Odds and vig conventions follow standard US sportsbook pricing (-110 on spreads and totals). The tax line is based on IRS Topic 419 and the Form W-2G instructions (rev. 01/2026); it is not tax advice.