How do you spot matches with value?
A price is not a prediction. Understanding the gap between that price and an estimated probability is the whole subject.
By The PRIZIFOOT team
A “value” bet is not a bet you think will win. It is a bet whose offered price is more generous than the event’s real probability. The two ideas are often confused, and that is the first source of error.
From price to probability
A decimal price converts into an implied probability by taking its inverse. A price of 2.50 corresponds to 1 ÷ 2.50 = 40%. A price of 1.40 corresponds to roughly 71%. That is what the market is asserting, operator margin included.
That margin is why the implied probabilities of a match always add up to more than 100%. On a classic 1X2 it often sits between 3 and 8%. A model that does not beat that margin wins nothing, even if it is “right a lot of the time”.
Measuring the gap
If a model estimates a probability p and the available price is c, the expected return on a unit stake is p × c − 1. Above zero, the bet has a positive expectation; below it, a negative one, whatever the gut feeling says.
- p = 45%, price 2.50 → 0.45 × 2.50 − 1 = +0.125, i.e. 12.5% expectation.
- p = 60%, price 1.50 → 0.60 × 1.50 − 1 = −0.10, i.e. −10%. A likely favourite is still a bad price.
The honest limit of the exercise
Everything rests on p. A gap computed from a badly estimated probability is not an opportunity, it is a measurement error presented to two decimal places. So the question that matters is never “how big is the gap” but “how well calibrated is my estimate”, that is: when the model says 60%, does the event really happen six times out of ten?
Move from theory to the match
Pick two teams and see what the model makes of it, without creating an account.
Analyse a match