Vig Removal and True Odds: Finding Your Edge
Every sportsbook builds in a commission (vigorish or 'vig') that ensures they profit regardless of outcome. Standard -110 odds on both sides of a bet mean the book takes ~4.5% of all money wagered. To find profitable bets, you must remove this vig to see the true implied probability and calculate your actual edge. This skill separates sharp bettors from recreational players.
How Vig Works
Example: Point spread with standard -110 odds on both sides
Team A -3 at -110 (52.4% implied probability)
Team B +3 at -110 (52.4% implied probability)
Total: 104.8% (should be 100%)
The extra 4.8% is the sportsbook's edge. They're essentially charging 4.8% commission on the action. If equal money comes in on both sides, they profit 4.8% guaranteed.
Calculating True Odds
To find true odds, remove the vig:
Step 1: Calculate total implied probability
- Team A: 52.4%
- Team B: 52.4%
- Total: 104.8%
Step 2: Normalize to 100%
- Team A true probability: 52.4% / 104.8% = 50%
- Team B true probability: 52.4% / 104.8% = 50%
Step 3: Convert to fair odds
- 50% probability = +100 fair odds (even money)
The book is offering -110 on a true +100 proposition - that's their profit margin.
Identifying Value
Once you know true odds, compare to your assessment:
Scenario: NBA Game
Book odds: Lakers -110, Celtics -110 (50/50 after vig removal)
Your assessment: Lakers 55%, Celtics 45%
Expected Value on Lakers:
- True probability: 55%
- Offered probability: 50% (after vig)
- Edge: 5%
- Bet $100: EV = (0.55 × $91) - (0.45 × $100) = +$5.05
You've identified a +EV bet by removing vig and comparing to your analysis.
Different Vig Structures
Vig varies by sport, bet type, and book:
- Point spreads: Usually -110/-110 (4.5% vig)
- Moneylines: Vig embedded in odds difference (varies)
- Totals: Typically -110/-110 (4.5% vig)
- Parlays: Heavy vig (10-20% or more)
- Props: High vig (10-15% common)
- Futures: Very high vig (20-30% typical)
Moneyline Vig Calculation
Moneylines are trickier - vig is hidden in the odds spread:
Example:
Favorite: -180 (64.3% implied)
Underdog: +150 (40% implied)
Total: 104.3%
Vig removal:
- Favorite true probability: 64.3% / 104.3% = 61.6%
- Underdog true probability: 40% / 104.3% = 38.4%
Fair odds would be approximately:
- Favorite: -160
- Underdog: +160
The gap between -160/+160 (fair) and -180/+150 (offered) is the vig.
Line Shopping and Vig
Reduced vig = more profit:
Scenario: You want to bet Team A -3
Book A: -110 (52.4% implied, 4.8% total vig)
Book B: -105 (51.2% implied, 2.4% total vig)
On a $100 bet:
- At -110: Win $91
- At -105: Win $95
That's $4 more profit per $100 wagered (4.4% better ROI) just from line shopping. Over hundreds of bets, reduced vig dramatically increases profit.
Practical Application
Always remove vig before assessing value. Calculate true odds to see what the market really thinks. Compare true odds to your assessment to find edge. Seek out reduced vig books (-105 instead of -110). Understand that beating the vig is the first hurdle - you need skill beyond that to profit. Track the vig you're paying across all books and bet types. Lower vig means you need less edge to profit. This is why professional bettors obsessively line shop and use books with lowest vig - every fraction of a percent matters over thousands of bets.