The Vig as a Percentage
The Vig (short for vigorish) is the commission charged by the sportsbooks on a contest. Let’s say that the money line odds for the Philadelphia Phillies and New York Mets are 140 and +130 respectively. As we explained in other articles, this means that you would have to bet $140 to win $100 if you choose Philadelphia and risk $100 to win $130 with the Mets. The vig is $10 (the difference between $140 and $130). But what is the sportsbook’s margin on the money line and why is it important to calculate the margin? It’s not difficult to calculate yourself when you know how. Using the same example, we first must convert the money line (ML) into a "percentage chance of winning" for each team. For favourites, that is the ML quote / (ML  100), so Philadelphia should win 140 / (140100) = 58.33% of the time. For the underdog, the calculation is 100 / (ML +100), so the Mets should win 100 / (130+100) = 43.48% of the time. If you add these two percentages together you get a figure of 101.81%. That extra 1.81% represents the bookie's hold or vigorish. There is also an easier way to find this out by using Pinnacle Sports’
MultiWay Calculator.
Go to the calculator, select money lines, and enter 140 and +130. The calculator will tell you that the “percent market” is 101.81% and the "theoretical hold" for the sportsbook (assuming balanced action in proportion to the odds) is 1.78%. This is also available for decimal odds and fractional prices. Another sportsbook may offer a different set of odds such as 140 and +130. The margin on this set of odds is 103.79% with a hold of 3.65%. This margin is more than twice as large as the first example, which means that $100 bettors would make $10 more in the first example. It just doesn’t make sense to pay more for
the vig
to the sportsbooks so make sure you shop around for the best odds. You may be surprised at the deals out there!
