What the vig is and how to measure it
The vig, or juice, is the margin a sportsbook builds into its prices. How to measure it as an overround and a margin, and why it matters.
Every market a sportsbook offers has a small fee built into its prices, never shown as a separate charge. That fee is called the vig, short for vigorish, and it is how a sportsbook aims to make money whichever side wins: when the money on each side is balanced, it keeps a share of the stakes. Once you know how to measure it, you can tell how much a market costs you and what the fair price underneath looks like.
Vig, juice, overround and margin
You will meet several words for the same idea:
- Vig or vigorish: the common North American term.
- Juice: another American name, often used for the -110 on a point spread.
- Overround: the British term. It describes how far a market's implied probabilities add up to more than 100%.
- Margin or hold: the share of all money staked that the sportsbook expects to keep.
The overround and the margin measure the same thing in two slightly different ways, so their numbers differ a little. Both are shown in the examples below.
Where the vig hides
Every price implies a probability: the chance of winning at which the price would break even (the implied probability guide covers how to work it out). In a fair market, the implied probabilities of every possible outcome add up to exactly 100%. A sportsbook lowers its prices a little (paying out slightly less than fair), so the implied probabilities are a little higher and the total comes to more than 100%. The extra is the vig. Books do not always spread it evenly: some outcomes, often the long shots, carry more of it than others.
Measuring it on a two-way market
Take a game where both sides of the point spread are priced at -110.
- The implied probability of -110 is 110 ÷ (110 + 100) = 52.38%.
- Both sides together add up to 52.38% + 52.38% = 104.76%.
- The overround is 104.76% − 100% = 4.76%.
To see the margin, imagine someone stakes 110 on each side, 220 in total. Whichever side wins, the book pays back 210 (the winner's 110 stake plus 100 profit) and keeps 10. That is 10 ÷ 220 = 4.55% of the money staked. The same figure comes from the overround: 1 − 1 ÷ 1.047619 = 4.55%, using the unrounded total of 220 ÷ 210.
A market priced -105 on both sides is cheaper. Each side implies 105 ÷ 205 = 51.22%, the total is 102.44%, the overround is 2.44% and the margin is 2.38%.
Measuring it on a three-way market
Football (soccer) match odds have three outcomes. Say the prices, in decimal, are home 2.10, draw 3.40 and away 3.60.
| Outcome | Price | Implied probability |
|---|---|---|
| Home | 2.10 | 47.62% |
| Draw | 3.40 | 29.41% |
| Away | 3.60 | 27.78% |
| Total | 104.81% |
The overround is 4.81%, and the margin is 1 − 1 ÷ 1.0481 = 4.59%. Markets with more outcomes, such as a tournament winner or a first goalscorer, often carry a much larger overround, because a little is added to every one of many prices.
Removing the vig
Scale each implied probability down so the market adds up to 100% again, and you have the fair price underneath. In the -110 and -110 market each side becomes 50%, a fair price of +100 or 2.00. The fair odds guide works through the method step by step, using the three-way market above, and shows how a consensus fair price is built from many sportsbooks. The calculator below does the arithmetic for you.
Read as American odds: −110
Read as American odds: −110
Margin 4.8%: the prices add up to 104.8%.
| Outcome | Implied | Fair chance | Fair price |
|---|---|---|---|
| Outcome 1 | 52.4% | 50.0% | +1002.001/1 |
| Outcome 2 | 52.4% | 50.0% | +1002.001/1 |
The fair price spreads the margin across the outcomes in proportion to their implied probabilities.
Why the vig matters to you
The vig is the cost of every bet. If the margin is spread evenly and the fair prices are right, a bet in a market with a 4.55% margin is expected to lose about 4.55% of its stake on either side. Some sportsbooks put more of the margin on long shots, so an underdog can cost more than that.
You cannot avoid the vig, but you can pay less of it. Different sportsbooks price the same outcome differently, so taking the best price on each side lowers the vig you face. If one sportsbook has a game at -110 on both sides and another has it at -105 and -115, the best prices are -105 on one side and -110 on the other. Together they add up to 51.22% + 52.38% = 103.60%, an overround of 3.60% instead of 4.76%.
That is what OddsKeepr does: it shows the best price for each outcome among the sportsbooks licensed where you are. How to compare odds explains how to read those prices, and the expected value guide shows how fair prices help you judge any price you see.
Gambling should stay within what you can afford to lose, and before you use any sportsbook it is worth checking that it is licensed where you are. If gambling stops feeling like entertainment, free and confidential help is listed for every country under where to get help.