Football Betting Prices & the Probability of Football Odds

Best Strategies for Betting

The Probability of Football Betting Odds

One question that gets asked a lot about football betting prices, is how do you translate them into probability? Or, to put it another way, how does probability determine betting odds? What does probability have to do with the odds themselves? Well, football betting predictions of course, have to rely on probability. This is what the odds are based upon so that you can actually have a bet. Say you picked up a rock and hid it in one of your hands and asked somebody to guess which hand it was in. The probability is at 50%-50% because it could only be in one of two hands (assuming you weren’t cheating and had dropped the rock!). Because of there being only two outcomes, this would translate as Evens in football betting, which means that there is an Even chance of getting this right (or wrong, depending on if you’re cup half-full or half-empty sort of person). That is pretty cut and dry. But, if you roll a dice then, just to put this into context, you then can only possibly have one of six outcomes. This in betting terms would be priced at 6/1, for you would have a one in six chance of picking the correct number.

Are football betting odds as simple as that? Of course not. Why? Because when two teams take to the field, three outcomes are possible, but not all of them would be evenly priced at 3/1 (or the punter having a one in three chance of getting the outcome correct) because they don’t all have an equal chance of happening. Manchester United have a greater chance of winning a match against Burnley for example, than Burnley does of beating Manchester United in that same match. There are not three equal sides to a match. Pricing all outcomes (home win, draw, away win) at 3/1 just wouldn’t be profitable for the online bookmaker.

Football betting prices are a little more complicated because betting odds are not solely based on something happening, and therefore the direct relation with probability and football betting odds needs to take a little twist. Think of a scale from 0 to 100. Zero would be the absolute certainty that something would not happen, and the number 100 would be the absolute certainty that an event will happen. At the halfway point would be the point at which it could absolutely go either way. But of course, you are not betting on the probability of something happening, that’s not the whole story behind a football bet.

When you are betting on a home win for example, you are betting on the probability of that home win happening against it not happening. So you are not just betting on a home win for a set figure somewhere on that sliding scale of probability, you are, for all intents and purposes, betting against other probabilities (a draw or an away win result) from happening. That cannot be represented as a straight probability figure, so this is where betting odds come in. To put this into betting terms, the factors of probability have to be converted into ratios of probability. The numbers are what you see on the market at your online bookmaker.

So, when you see those prices, what do they mean in terms of probability? Naturally mathematics are on your side, and whether you were paying attention in class or not, there are a couple of simple ways to work out the real probability of what goes on behind a bet. This is relatively easy to do with decimal betting, as whatever the odds are which have been presented say for a Home win, you simply divide that by 100. So if a Manchester United home win is decimally priced at 1.25 then you simply do the math like so:

100 divided by 1.25 (the odds) which gives you a figure of 80.0 which means that the bookmaker believes that there is an 80% chance of United winning the match in question. That, in decimal odds, is all that you do to work out the probability percentage of an event happening, in this case, the event of a Manchester United win against a draw and an away win. For fractional bets, the math is just a little more elaborate looking, but just as simple to calculate.

Let’s take a recent actual game priced with fractional odds at online bookmaker SportingBet
Barcelona to win: 2/9
Draw: 21/5
Sevilla to win: 10/1

How do we convert this to probability? Let’s take a fraction bet and assign it letters to build our equation.
Barcelona to win: y/z

So the odds to probability percentage equation is this:
z divided by (y + z) x 100

For the above Barcelona 2/9 example it would be:
9 divided by 2+9 x 100
= 82% probability that Barcelona will win according to the bookmaker.

Let’s just do a Sevilla win to show this formula again:

Sevilla to win: 10/1 (Sevilla to win: y/z)

Apply equation:
z divided by (y + z) x 100

Translates to:
1 divided by (1 + 10) x 100 = 9%

So you take the right hand side of the fractional football betting odds, and divide that by the two halves of the bet added together, then multiply by one hundred to give your probability percentage. The important thing to consider, and going back to the sliding scale of 0 to 100, is that the probability percentages for a match, just as in the above example if you work it all out yourself, will not add up to 100%. There is a very good reason for this, and it is called profit margins by bookmakers and is something that will always be there. Also, that no matter how high the probability, it is of course just a guideline, as anything can happen in football betting. Naturally the favourites do get upset now and again and results do go against probability. But, bearing that in mind, football betting has a lot to do with averages, and if you do back favourites solely week in week out, you will get returns, albeit small ones. So, it is up to the punter whether to risk more for small accumulation of profits, or go for the big underdog winners. Let probability be your guide.


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