What is Vig in Sports Betting?

Vig — short for vigorish, and also called juice, margin, or overround — is the built-in commission a bookmaker bakes into their odds. It's the reason the house wins long-term and the reason casual punters slowly bleed out even when they pick winners at roughly the expected rate. Understanding vig is the first step to beating it.

The clearest way to see vig is a coin toss. A fair market on a 50/50 event would offer $2.00 on heads and $2.00 on tails — stake $100 on either side and get $100 profit when you win. A bookmaker won't offer that. They'll offer something like $1.91 / $1.91. The true probability of each outcome is still 50%, but the odds imply a probability of 52.4% on each side (1 / 1.91). Those two implied probabilities add to 104.8%, and that extra 4.8% is the vig.

To calculate vig on any two-way market, convert each odds to implied probability (1 / odds), sum them, and subtract 1. For a three-way market — like a soccer match with home/draw/away — the same formula works, you just add all three implied probabilities. If they sum to 1.07, the bookmaker's margin is 7%.

Vig varies dramatically by market and bookmaker. Head-to-head markets on major sports are often 2–4%. Futures, specials, and prop markets can carry 15–25% or worse. Racing markets are often 20%+. The higher the vig, the harder it is to profit — which is why professional bettors focus on markets with low built-in margins, shop for the best price across bookmakers, and exploit promotional offers that effectively reduce or eliminate the vig.

Arbitrage betting beats the vig by combining odds from two different bookmakers whose lines, taken together, add to less than 100% — a situation where the same event is priced as if the vig is negative. +EV betting beats it by finding individual prices that are mispriced relative to sharp reference markets. Matched betting using bonus bets effectively eliminates the vig on the bonus portion of your stake entirely.

Our Arb Scanner and +EV Finder are designed specifically to exploit vig across Australian bookmakers. Most punters never calculate vig before placing a bet — they just take the price in front of them. That's exactly what bookmakers are counting on.