Odds explainer
Implied probability
How to turn a UK football price into a percentage, why three match-result prices will not add to 100, and what that gap is for.
Implied probability is the percentage a price would represent if the book had no margin and no opinion other than the number on the screen. It is a translation, not a truth.
The conversion
For decimal odds d, implied probability is 1 ÷ d.
- 2.00 → 50%
- 3.50 → about 28.6%
- 1.50 → 66.7%
For fractional a/b, it is b ÷ (a + b).
- 5/2 → 2 ÷ 7 → about 28.6%
- 4/6 → 6 ÷ 10 → 60%
- evens → 50%
Those two routes agree when you converted the odds correctly. If they do not, you mixed profit and return.
The overround
Add the implied percentages for home, draw, and away on a typical 1X2. You will get more than 100% — often 105% to 110% on a liquid Premier League match, more on a thin market. The surplus is the book’s margin, sometimes called the overround or the juice.
It is not a conspiracy and it is not a rounding error. It is the cost of using their coupon. A “fair” set of prices would add to 100%. You will not be offered that set.
You can remove the margin, roughly, by dividing each implied probability by the total of all three. That gives a normalised picture of how the book has split the match. It is still their picture. It is not a model of the teams.
What implied probability is not
It is not the chance the team will win. It is not a tip. It is not a reason to “fade the public”. It does not become more true because you typed it into a spreadsheet.
It is a way to notice when a price is very short. A 1.20 favourite is implying more than 80% before you even look at the other two outcomes. You need a strong football reason to lay that much of your own money against a small profit. Wanting the team to win is not a reason.
Accas multiply the silence
An accumulator multiplies decimal prices and also multiplies the chance that one dull 1-1 ruins the ticket. The implied probability of a four-fold is not four friendly percentages added together. It is the product of the individual implied probabilities — and that is before the book’s margin on each leg. See accumulators.
How we use this on Footballbet
We use implied probability to explain a price, not to sell one. We will not publish a “value bet” table. We will not pretend a reviewer’s hunch beats a licensed book’s trading bench.
If the arithmetic is the bit you came for, sit with it until the percentage feels boring. Boring is the correct mood for money.
We are not a bookmaker. 18+ only. If you are chasing a percentage, stop and visit BeGambleAware.