How Vig (Juice) Actually Works, and How to Calculate Your Break-Even Win Rate

Published September 12, 2026 · 9 min read · By the OddsLighthouse Editorial Team

Bet $110 to win $100 on either side of a coin-flip game, and you can lose money even if you call the coin correctly half the time. That gap — the extra amount a sportsbook charges relative to the true odds of a bet — is the vig, short for vigorish, also called juice. It's baked into essentially every line at every US sportsbook, and most bettors have a rough sense it exists without ever having worked out exactly what it costs them or how much win rate it forces them to clear before they're actually making money.

What vig is, in plain terms

Every price a sportsbook posts is built from two things: its estimate of how likely an outcome is, and a built-in margin on top of that estimate that guarantees the book a profit if it books roughly equal money on both sides. That margin is the vig. It's not a separate fee added at checkout — you won't see a line item for it on your bet slip — it's baked directly into the number itself, which is exactly why so many bettors don't think about it directly even though they're paying it on every single wager.

The mechanism is simple once you see it: if a coin flip were priced fairly, both sides would be +100 (bet $100 to win $100, reflecting a true 50/50 shot). Instead, US sportsbooks typically price a pick'em game at -110 on both sides. That -110/-110 pricing is the standard vig baseline for spreads and totals, and it's the number worth understanding before anything else on this list.

Standard -110 pricing, and why both sides can't both be fair

Convert -110 to implied probability using the standard formula for negative odds — odds ÷ (odds + 100) — and you get 110 ÷ 210, or about 52.4%. Do that for both sides of a -110/-110 market and add the two numbers together: 52.4% + 52.4% = 104.8%. A true coin flip only needs to add up to 100%. That extra 4.8 percentage points is the vig — the sportsbook's cut, expressed as the amount the two implied probabilities overshoot 100% by.

That's why it's mathematically impossible for both sides of a standard spread or total to be "good bets" at the same time — someone is always laying a price slightly worse than the true odds, and usually both bettors are, since the book prices both sides above fair value rather than one side above and one below.

The break-even win rate formula, with a worked example

Because of the vig, you don't need to win 50% of your bets at -110 to break even — you need to win more than that, since a loss costs you more than a win nets you. The formula for break-even win rate at any negative price is:

Break-even win rate = risk ÷ (risk + win)

At -110, you risk $110 to win $100, so the formula is 110 ÷ (110 + 100) = 110 ÷ 210 ≈ 52.38%. Here's what that actually looks like over 100 bets of $110 each, assuming you win exactly at the break-even rate:

Win exactly 52.38% at -110 across a large enough sample and you land at dead even, before accounting for anything else. Win 50% — a genuine coin flip — and you're actually down money: 50 wins at +$100 is $5,000, but 50 losses at -$110 is -$5,500, for a net loss of $500 per 100 bets. That's the entire mechanism of vig in action: it converts a fair coin flip into a losing proposition unless you can beat the number the book is offering.

How vig changes at different prices

Vig isn't fixed at 4.8% — it moves depending on the price and, importantly, it isn't always split evenly between both sides. Two things affect it: how far a line is from even money, and how a specific book chooses to price its margin across favorite and underdog. A few common prices and their break-even win rates:

Notice the pattern: the more lopsided the price, the higher the win rate you need to clear to profit at that specific number — which is intuitive once you think about it as "how much am I risking to win a dollar." But it's also worth knowing that books don't always split their margin evenly across both sides of a two-way market. Some markets carry more vig on the favorite side, some on the underdog side, and thinner markets like player props or alternate lines often run noticeably higher total vig than a main spread or total, simply because there's less action to balance and more model uncertainty for the book to protect against.

Why a few cents of juice adds up over a season

A gap between -105 and -120 on the same bet looks trivial on a single wager, but it compounds fast across volume. Say a bettor places 500 bets a season at $50 each, roughly break-even against the market's true probability before vig. At -110 across the board, that bettor needs to hit 52.4% to break even. At -120, they'd need 54.5%. That two-point gap in required win rate is often the entire difference between a hobbyist who loses steadily over a season and one who treads water — and it's a gap created purely by where they happened to place the bet, not by anything about the game itself.

This is the actual math behind "line shopping" advice you'll see repeated everywhere: comparing the same bet across multiple sportsbooks before placing it isn't a minor optimization, it's directly lowering the win rate you need to clear to be profitable. A bettor who consistently finds -105 instead of -110 on identical bets is giving themselves roughly 1.2 percentage points of win rate back, every single time, with zero change to their handicapping.

Common misconceptions about vig

• "Low vig means the book thinks it's a true coin flip." Not necessarily — a book can price a game at -110/-110 because it genuinely sees it as close, or because it's still building liability and hasn't shaded the number yet. Vig level and the book's actual model confidence are two different things.
• "Vig is the same everywhere." It isn't. Different books, different sports, and different bet types (spreads vs. totals vs. player props vs. parlays) all carry different average vig, and some markets are structurally worse for the bettor regardless of how sharp the pick is.
• "If I'm right more than half the time, I'm profitable." Only true at true even-money pricing, which barely exists at retail sportsbooks. At standard -110, "more than half the time" isn't enough — you need to clear roughly 52.4%, and that threshold moves at every other price.

None of this means vig makes betting unbeatable — plenty of bettors clear their break-even threshold consistently. It does mean the threshold is real, it's higher than 50% on almost every standard bet, and it moves depending on the specific price you're getting. For more on how to read the prices themselves, see our guide to how betting odds work, and for the process of comparing prices across books, see our guide to closing line value.