Why the board never adds up
Every two-sided market implies more than 100%. That gap is the house's cut.
-110 on both sides looks like a coin flip priced fairly. It is not, and the gap is the reason most bettors lose.
The two numbers on that screen add up to more than everything that can happen.
Take a coin flip. Both sides should be +100 — 50% each, adding to 100%. No book prices it that way. You will see -110 on both sides, which implies 52.4% each, and 52.4 + 52.4 is 104.8%.
-110 and -110 imply 104.8% between them. The extra 4.8% is the house's cut.
That extra 4.8% is the book's margin, charged on both sides so that whichever way the game goes, the house keeps a slice. The trade calls it the vig, the juice, or the hold.
What it costs the average bettor
At -110 both ways you need to win 52.4% of your bets just to break even. Not 50%. Someone picking games perfectly at random loses money forever at that price, slowly, without ever making an obviously bad decision. This is the single most important number in betting and almost nobody who loses money knows it.
Where the vig is fattest
Books are confident about main lines and much less confident about everything else, and they price that uncertainty in. A major-league spread might be -110/-110. The same book might run -115/-115 on whether a player gets three rebounds or four, because that is genuinely harder to model. Fatter margins mean more room for the number to be wrong — which is why the softest prices are so often away from the main line.
Every fair price here has had the vig stripped out before anything is compared. Comparing one raw price to another tells you which book charges less, not whether either is worth betting.
1 of 3
At -110 on both sides, what do you have to hit just to break even?
2 of 3
Two sides of a market imply 104.8% between them. What is the extra 4.8%?
3 of 3
Why does a book often run -115/-115 on a small player prop and -110/-110 on the main spread?
At -110 both ways you have to be right 52.4% of the time just to break even. Beating the vig is the whole game.
Terms from this lesson
Education, not betting advice. 21+. Gambling problem? Call or text 1-800-GAMBLER.