How Do Sportsbooks Make Money? The Vig Explained

Understanding the House Edge That's Built Into Every Bet

By Kara Hendricks  |  Last updated: March 2026  |  8 min read

You've placed hundreds of bets. But have you ever wondered why even a coin-flip bet at a sportsbook pays you $91 on a $100 wager instead of $100? The answer is the vig — and understanding it changes how you approach sports betting.

The vig isn't a trick or a hidden fee. It's the fundamental mathematics of how every sportsbook operates. Once you understand how it works, you'll think differently about line shopping, market selection, and what "value" actually means in betting.

What Is the Vig (or Juice)?

The vigorish (vig) — also called juice, margin, or overround — is the built-in commission that sportsbooks take on every bet. It's not charged explicitly as a separate line item. Instead, it's baked directly into the odds themselves, making it invisible to most casual bettors.

The clearest way to understand it is with a simple example. Imagine a fair coin flip between two evenly matched teams. In a truly fair bet, you'd wager $100 and win $100. But at a sportsbook, both sides are typically offered at -110. That means to win $100, you must bet $110.

Here's what happens when the book takes equal action on both sides:

• 10 bettors put $110 each on Team A: total in = $1,100
• 10 bettors put $110 each on Team B: total in = $1,100
• Total collected: $2,200
• Winning side paid out: $1,100 wagered + $1,000 winnings = $2,100
• Sportsbook keeps: $100

The sportsbook collected $2,200 and paid out $2,100, keeping $100 regardless of which team won. That's the vig at work — a mathematical guarantee of profit when the book is balanced.

The Math Behind the Vig

The vig shows up in something called implied probability. Every set of odds implies a probability of winning. At -110, the implied probability is calculated as:

$110 ÷ ($110 + $100) = 52.38%

If both sides of a 50/50 market are priced at -110, both have an implied probability of 52.38%. Add them together:

52.38% + 52.38% = 104.76%

Probabilities must add up to 100% in reality. The extra 4.76% is the sportsbook's margin — the overround. This is also why you must win 52.38% of all -110 bets just to break even. You're not fighting 50/50 odds; you're fighting 52.38% odds.

The table below shows how the break-even rate shifts with different standard odds:

The difference between -105 and -115 might look trivial. But across hundreds of bets, the bettor at -105 is fighting a much smaller mathematical headwind than the bettor at -115. Over a full season, those basis points add up to real money.

Real NHL Example — How the Vig Works in Hockey

Let's look at how this plays out in a real game. Say the Toronto Maple Leafs are hosting the Montreal Canadiens, and the sportsbook posts:

• Toronto Maple Leafs: -130 (bet $130 to win $100)
• Montreal Canadiens: +110 (bet $100 to win $110)

Now convert both to implied probabilities:

• Leafs at -130: $130 ÷ ($130 + $100) = 56.5%
• Canadiens at +110: $100 ÷ ($100 + $110) = 47.6%
• Combined: 56.5% + 47.6% = 104.1%

The overround is 4.1% — the sportsbook's theoretical margin on this game. No matter which team wins, the book profits as long as it's taken roughly balanced action on both sides.

This leads to an important realization: you're not betting against the sportsbook. You're betting against other bettors, with the sportsbook acting as a commission-taking middleman. When you win, you're paid from what losing bettors wagered — minus the sportsbook's cut.

Why Lines Move — The Sportsbook's Real Goal

Sportsbooks are not in the business of predicting outcomes. Their primary goal is to balance their book — to take equal action on both sides of every market so they profit from the vig regardless of the result.

When too much money flows onto one side, the sportsbook is exposed to a real loss if that side wins. Their response: move the line to make the heavy side less attractive and the light side more attractive, until money flows back into balance.

This is called line movement, and it's one of the most useful signals available to a bettor. If the Leafs open at -130 and move to -155 by game time, something significant happened — either sharp bettors (professionals with large stakes) hammered one side, or injury news broke, or a major public trend pushed the number. Learning to read line movement is a skill in itself.

Sharp bettors — the small percentage of professional gamblers — watch line movement to understand where sophisticated money is going. "Reverse line movement" (when the line moves opposite to the betting percentages) is a particularly strong signal that sharp money is at work.

Different Types of Vig

The vig is not a fixed number. It varies by market type and by sportsbook:

Standard vig (-110/-110): The most common pricing on spreads and totals in Canada. You're paying roughly a 4.76% margin on every bet.

Reduced vig (-108/-108 or -105/-105): Some sportsbooks, particularly for high-volume markets like NFL and NHL mainlines, offer reduced juice. Moving from -110 to -105 lowers your break-even rate from 52.38% to 51.22% — a meaningful improvement for serious bettors.

Moneylines: The vig is built into the gap between the favourite's negative number and the underdog's positive number. A fair moneyline on an evenly matched game would be +100/+100. Instead you typically see -110/+100 or -115/+105 — the spread between those numbers represents the margin.

Totals (over/under): Same principle as sides — both over and under are typically priced at -110, creating the same 4.76% margin.

Vig-free promotions: Occasionally, sportsbooks offer "no-vig" markets as promotional tools. These are genuinely good value and worth using when available.

How to Account for the Vig in Your Betting

Understanding the vig isn't just academic — it has direct practical implications for how you should approach betting.

1. Shop lines across multiple sportsbooks. The single most impactful habit a serious bettor can develop. If you find -108 at one book versus -115 at another on the same game, the -108 is worth taking. Over a season of NHL bets, the cumulative difference in break-even rates produces a measurable impact on your results.

2. Focus on low-vig markets. Mainline moneylines and spreads on major markets (NHL, NFL, NBA) carry margins of roughly 3.5–5%. Prop bets and futures carry margins of 8–12% or more. The more obscure the market, the more the book is charging for the privilege of betting it.

3. Use no-vig calculators. These tools take both sides of a line, convert them to implied probabilities, strip out the overround, and give you the "true" probability the sportsbook is implying. Comparing that true probability to your own assessment of the game is the foundation of finding value. If the book implies 52% and you believe a team has a 57% chance, that's a value bet.

4. Think in terms of long-run win rates, not individual results. At -110, you need to win 52.38% of bets to break even. That means even a skilled bettor hitting 55-56% over a large sample is doing well. The vig makes small edges matter — and makes casual "gut-feel" betting a slow money drain.

The Vig Varies by Sport and Market

Not all markets are priced equally. Understanding where the margin is highest helps you allocate your betting activity more efficiently.

NHL and NFL mainlines: Typically 4–5% margin. These are the highest-volume markets, sportsbooks price them competitively, and sharp money keeps them efficient.

NBA and soccer mainlines: Similar to hockey and football — 4–5% on most games, tighter on marquee matchups.

Player prop bets: Commonly 8–12% margin. These markets are harder for sportsbooks to price precisely, so they charge more for the uncertainty. Anytime Goalscorer props in hockey, for example, frequently carry double-digit margins.

Futures: Often 10–15% or more. Betting on Stanley Cup winners before the season starts might look appealing at +800, but when you add up the implied probabilities of all 32 teams, you often reach 115–120% total — a massive overround.

Live betting: The highest vig of all, often 8–15%. Sportsbooks are pricing on the fly with rapidly changing information, so they widen margins substantially to protect themselves. Live betting is entertaining but the worst value environment for most bettors.

The practical takeaway: if you're serious about long-run results, spend most of your time in mainline markets where competition between sportsbooks keeps the vig tight.

Frequently Asked Questions

What is the vig in sports betting?

The vig (vigorish) is the commission built into betting odds that ensures sportsbooks profit regardless of the outcome. At the standard -110 odds, bettors must risk $110 to win $100. When equal action is taken on both sides, the sportsbook keeps $10 per $210 wagered — a 4.76% margin.

What is the break-even win rate for sports betting?

At standard -110 odds, you need to win 52.38% of your bets to break even. This is the mathematical hurdle imposed by the vig. At reduced vig (-105), the break-even rate drops to 51.22%.

Do Canadian sportsbooks have higher vig than US books?

Vig rates are broadly similar across Canadian and US licensed operators, typically 4–5% on main markets. The primary variable is market type — prop bets and live betting consistently carry higher margins than mainline spreads and moneylines.

How do I reduce the impact of the vig?

The two main approaches are: (1) shopping lines across multiple sportsbooks to find the best available price, and (2) focusing on markets with lower vig such as mainline moneylines and spreads rather than props and futures.