Implied Probability Calculator
Turn a price into the chance it implies. Add every outcome in the market to see how much margin the bookmaker has built in, and the chance of each outcome once it is taken out.
Published
What implied probability means
Decimal odds are the total return per dollar staked, so the chance a price implies is one divided by the price: 2.50 implies 40%, 1.80 implies 55.56%. It is the win rate at which a bet at that price breaks even, not the real chance of the outcome. Every price includes the bookmaker's margin, so the implied chances across a market add up to more than 100%.
Overround, hold and no-vig chances
The amount a market's implied chances add up to above 100% is the overround. The hold is the share of every dollar staked the bookmaker keeps if the money on each side balances: 1 − 1 ÷ the total book, always a little smaller. Divide each implied chance by the total book and you get the no-vig chances, which add up to 100% again. The no-vig calculator turns them back into fair odds, and the vig calculator says whether a market's margin is wide or sharp.
The formula
total book = 1/O₁ + … + 1/Oₙ
overround = total book − 100%
no-vigᵢ = (1/Oᵢ) ÷ total book
Worked example
A head-to-head at 1.80 and 2.05. The prices imply 55.56% and 48.78%, which add up to 104.34%: an overround of 4.34% and a hold of 4.16%. Divide each by 1.0434 and the no-vig chances are 53.25% and 46.75%, fair prices of 1.88 and 2.14.
A chance worth holding the price against
HaterPicks projects player-prop lines and grades every projection win or lose against the result, so there is a number to compare the implied chance with. Free account · no card.
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FAQ
How do you calculate implied probability from decimal odds?
Divide 1 by the decimal odds and multiply by 100. At 2.50 that is 1 ÷ 2.50 = 0.40, or 40%. At 1.80 it is 55.56%. It is the win rate at which a bet at that price breaks even.
Why do the implied probabilities add up to more than 100%?
Because every price includes the bookmaker’s margin. A fair two-way market at even money would be 2.00 and 2.00, 50% each. Bookmakers price it at 1.91 and 1.91 instead, 52.36% each, and the extra 4.71% is the overround.
What is the difference between the overround and the margin?
The overround is how far the total book is above 100%: 1.91 on both sides is 104.71%, a 4.71% overround. The margin, or hold, is the share of all money staked the bookmaker keeps on a balanced book: 1 − 1 ÷ 1.0471 = 4.50%. Both describe the same market.
How do I use implied probability?
Compare it with your own estimate of the chance. If you rate a team a 45% chance and the price implies 40%, the price is longer than it should be; if you rate it 35%, it is too short. The EV calculator turns that difference into dollars.