Understanding Vig: What -110 Really Costs
At -110 odds you risk 110 dollars to win 100, which implies a 52.4 percent probability. Both sides of a standard prop are priced at -110, so the market adds up to 104.8 percent, and that extra 4.8 percent is the vig: the sportsbook's built-in fee on every bet, charged whether you win or lose.
What -110 actually says
American odds of -110 mean you risk 110 to win 100. Converting to implied probability: risk divided by total return, 110 / 210, is about 52.4 percent.
Read literally, the book is charging you a price that assumes the bet wins 52.4 percent of the time. For a market that is genuinely a coin flip, that extra 2.4 points is not an opinion about the game; it is the fee.
The 104.8 percent market
Add both sides of a -110 / -110 prop and the implied probabilities total about 104.8 percent. Real probabilities must sum to 100, so the extra 4.8 percentage points is the book's margin, called the vig, the juice, or the overround.
The margin means the book profits regardless of the outcome if it attracts balanced action. Bettors collectively pay 104.8 percent for 100 percent of the possible outcomes, and the difference is the house's cut of the market.
What vig costs you over time
At -110, the breakeven win rate is 52.4 percent. Win less than that and you lose money even while winning more bets than you lose, which is the quiet way most bettors lose: not on bad picks, but on the tax.
Framed as expected value: a true 50/50 bet at -110 loses about 4.5 cents per dollar staked on average. Over hundreds of bets, that drip is the entire difference between breaking even and a losing year.
Not all markets charge the same
Main game lines at major books are the cheapest markets, often near the standard -110 on each side. Player props typically carry wider margins, with sides at -115 or -120 more common, because prop markets are smaller and books protect themselves against sharp, informed action.
Margins also grow with market complexity. Three-way soccer markets spread the vig across three outcomes, and parlays compound it across every leg, which is why the products books advertise hardest are usually the ones that hold the most.
Line shopping reduces the tax
Vig varies by book on the same market at the same moment. One book posts a prop at -115 on each side while another has the same line at -108, and taking the better price is a direct rebate on the fee.
You cannot avoid vig entirely at sportsbooks, but consistently paying the lowest available version of it compounds the same way the tax itself does. That is the entire, unglamorous case for comparing odds before every bet.
Prediction markets: a different fee model
Exchanges like Kalshi and Polymarket do not build a margin into the price. Contracts trade between buyers and sellers, and the platforms make money on explicit trading fees, while the gap between the best buy and sell prices, the spread, acts as a real cost too.
The costs are structured differently rather than absent: visible fees and spreads instead of an embedded markup. That structural difference is one reason prediction market prices regularly disagree with sportsbook odds on the same outcome.
Frequently asked questions
Why is -110 the standard price?
Convention and margin. Charging 110 to win 100 on both sides gives the book roughly a 4.5 percent hold on balanced action, a rate the US market settled on decades ago for spreads and totals. Books deviate from it freely on props and promotions.
What is hold percentage?
Hold is the share of total money bet on a market that the book expects to keep. It is the practical expression of the overround: a -110 / -110 market implies 104.8 percent in probabilities, which works out to a hold of roughly 4.5 percent of the handle.
Is lower vig always better?
For the same line, yes: -105 strictly beats -115 on the identical bet. Across different lines it is a trade-off, because a friendlier line at a worse price can beat a sharper price at a worse line. Compare the combination, not the vig alone.