In this article we’ll explain why you should learn how to calculate a bookie’s overround and how it will help with your betting. The overround can go by many names; overround, vig, juice or commission and the reason we need to be able to calculate it is so that we can see how much money a bookie is making on selections. Let’s start with an example of a betting event with has two outcomes; Over 2.5 goals in a match.

Bookie’s Overround

Next weekend, Manchester United host Liverpool at Old Trafford. At the time of writing the odds for Over/Under 2.5 goals are 1.81 and 2.10 with Pinnacle. So, a little about Pinnacle first. Pinny are well-known as being one of the ‘fairest’ bookies on the market. This means they tend to ‘charge’ the least commission per market and they let the market dictate which way prices go. So, they usually start with prices for events with two outcomes around the same price, 1.98, then as money is put into the market by punters the odds will change depending how which side gets the most money. So in this example, the market is expecting Over 2.5 goals because the price opened at 1.98 and has fallen to 1.81.

Now, let’s calculate the overround. 1/1.81 = 0.55248 x 100 = 55.29. Over 2.5 goals has a probability of 55.29% according to those odds. 1/2.10 = 0.47619 x 100 = 47.62, Under 2.5 goals has a probability of 47.62%. Let’s add those together. 55.29 + 47.62 = 102.91. Hold on now, how can probabilities equal more than 100%? Well, this 2.91 percent is what the house wins no matter the result. Bookies don’t really care what the result of the match is, so long as they’re making a good commission they’re happy. And the reason Pinny ‘charge’ such a low commission is because they want high rollers betting large amounts. The same goes for the big Asian bookies like SBOBet, Dafabet, 188Bet etc. Because their client base is so huge, they don’t have to add large overrounds to their odds to continue to make money. MarathonBet is worth a mention here too, while not an Asian bookie, of the current crop of UK they charge the lowest commission regularly.

Calculate a Bookie’s Overround

Let’s compare those Pinny odds and the odds for Over/Under from a highstreet bookies, we can’t name them, but they’re the one with the red logo. Their odds for Over/Under 2.5 goals in the Manchester United - Liverpool match are 1.70 and 2.0. Let’s calculate their overround. 1/1.70 = 0.5882 x 100 = 58.82%. 1/2.0 = 0.5 x 100 = 50%. 58.82 + 50 = 108.82. Woof, these guys are making 8.82% on the wagers taken, while Pinny were taking just 2.91%. Who should you be betting with?

Bookies like Pinny, MarathonBet and the big Asian one are usually called ‘Hard Books’ and the highstreet bookies around Europe are called ‘Soft Books’.

Now, let’s look at how to get the fair odds for both those bookies. In the Pinny case, the implied probabilities were 55.29% and 47.62% and the total calculated was 102.91. So we divide these numbers; 55.29/102.91 = 53.726. 1/0.53726 = 1.86. Over 2.5 goals should be priced at 1.86. With Unders; 47.62/102.91 = 46.273. 1/0.46273 = 2.16. So, Unders should be 2.16.

For the second one the implied probabilities were 58.82% and 50%. We need to divide them by the overround of 108.82. 58.82/108.82 = 54.052. 1/0.54052 = 1.85. Over 2.5 goals should be 1.85 with them. For Unders, 50/108.82 = 45.947. 1/0.45947 = 2.17. Under 2.5 goals should be 2.17 with the highstreet bookies.

We can see then that by calculating a bookie’s overround, commission, juice, vig, whatever you want to call it you can get to see how much of a ‘charge’ they have on their odds and you can calculate the actual probability of an event occurring.

Something to remember with the ‘softbooks’ is that they’re more inclined to offer odds based on what their customers will go for, the ‘hardbooks’ offer prices that are dictated purely on how the market moves thanks to people placing wagers. We can see then that using hardbooks offer better and fairer odds and really, those are the ones you should be using. Betting Exchanges are quite similar. However, depending on where you live and which one you use different commissions apply.