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Implied probability

Implied probability is the probability that a set of odds suggests. You compute it by dividing 1 by the decimal odds: odds of 2.00 imply 50%, odds of 4.00 imply 25%. It lets you compare odds to your own estimate to spot a value bet.

Converting odds into a probability is the basic reflex for judging a bet: instead of looking at the potential payout, you ask whether the outcome really has as much chance of happening as the price suggests. Odds of 1.25 imply 80%, odds of 5.00 imply 20%.

The implied probabilities of a match's three outcomes sum to more than 100%: the excess is the bookmaker's margin (the « vig » or overround). Each raw implied probability is therefore slightly inflated. To get a « clean » estimate, you divide each one by the total so that they add up to 100% again.

Implied probability doesn't tell the truth about the match: it sums up the market's view, plus the margin. It is still a useful benchmark, because a liquid market pools a lot of information. It is also why a prediction whose probabilities add up to exactly 100% is easier to read than raw odds: there is nothing to strip out before comparing.

Example

Odds 2.50 → implied probability = 1 ÷ 2.50 = 40%.

How Elofoot uses it

Elofoot shows probabilities directly, with no margin: the 1X2 percentages are whole numbers that add up to exactly 100%. When a Polymarket market (a real-money prediction market) is liquid enough, its 1X2 counts for 65% and the Poisson model for 35%; otherwise, the model stands alone. These probabilities can serve as a point of comparison with the implied probability of a price.

Betting involves risks: losing money, debt, addiction. Betting is for adults only. Never stake more than you can afford to lose. Elofoot is a data analysis tool: it takes no bets and no prediction is guaranteed.

Frequently asked questions

How do you convert odds into a percentage?
Divide 1 by the decimal odds, then multiply by 100. Odds of 1.80 correspond to 1 ÷ 1.80 ≈ 55.6%.
Why do implied probabilities add up to more than 100%?
Because the bookmaker builds its margin into the odds. The excess above 100% is its commission, not an extra chance.
How do you remove the margin from implied probabilities?
The simplest method is to divide each implied probability by their sum. The three outcomes then add back up to 100%.

See also

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