No-Vig Fair Odds

What is Vig (Vigorish)?

Vigorish, commonly called "vig" or "juice," is the bookmaker's profit margin built into betting odds. Rather than offering true 50/50 odds at +100 / +100, sportsbooks typically price both sides of a market at -110 / -110. This creates an overround—the sum of implied probabilities exceeds 100%.

Example:

• Team A: -110 → 52.38% implied probability
• Team B: -110 → 52.38% implied probability
• Total: 104.76% (the extra 4.76% is the bookmaker's edge)

This overround ensures the book profits regardless of outcome. If 100 people bet $100 each on Team A and 100 people bet $100 on Team B, the book collects $20,000 in wagers. When Team A wins, they pay out ~$19,090 (100 × $190.90 payout at -110 odds), keeping $910 profit.

Methods for Removing Vig

This calculator uses the multiplicative method (also called proportional normalization), which scales each implied probability down proportionally so they sum to 100%.

Fair Probability = Implied Probability / Total Implied Probability

For -110 / -110 odds: Fair probability for each side = 52.38% / 104.76% = 50.00%

Alternative methods exist (additive, power, Shin), but multiplicative is most common because it:

• Preserves the ratio between implied probabilities
• Works for any number of outcomes (2-way, 3-way, props)
• Is mathematically simple and transparent

Finding Value with No-Vig Odds

Once you have fair odds, compare them to your own probability estimates or to odds at other sportsbooks. A bet has positive expected value (+EV) when the offered odds are better than the fair odds.

Example:

• Sportsbook offers Team A at +120 (implied probability: 45.45%)
• Fair odds after removing vig: +100 (fair probability: 50%)
• Since +120 offers better value than +100, you have +EV (you're getting 45.45% implied when the fair probability is 50%)

Consistently betting +EV opportunities is the foundation of profitable sports betting. Even small edges (2-3%) compound over hundreds of bets.

Vig Varies by Market

Not all markets have the same vig. Competitive markets (NFL spreads, NBA totals) typically have 4-5% vig, while less liquid markets can have 10-20% or more:

• Low vig (3-5%): Major league spreads/totals, popular moneylines
• Medium vig (5-10%): Player props, same-game parlays, less popular sports
• High vig (10-25%): Exotic props, futures far from settlement, low-volume games

Always calculate vig before evaluating whether a bet offers value. A seemingly "good" prop at +300 might be terrible value if the fair odds are +500 after removing 15% vig.

Limitations of No-Vig Calculations

No-vig odds assume the bookmaker's prices are informationally efficient—that the only difference between market odds and fair odds is the built-in profit margin. This isn't always true:

• Favorite-longshot bias: Longshots (+400 or higher) are often overpriced even after removing vig
• Public betting patterns: Books may shade odds toward popular teams, creating inefficiency
• Stale lines: Odds may not reflect late-breaking news (injuries, weather, lineups)

Use no-vig odds as a starting point, then refine with your own models, injury analysis, and market timing.

Using This Calculator Effectively

Step-by-step workflow:

• 1. Enter odds from a sportsbook for all outcomes in a market
• 2. Review the total implied probability—higher values indicate more vig
• 3. Compare no-vig odds to your own probability estimates or to odds at other books
• 4. If you find a meaningful discrepancy (2%+ edge), consider it a +EV opportunity
• 5. Use the Positive EV calculator to determine optimal stake size

For best results, track no-vig odds across multiple sportsbooks. If Book A has Team A at -105 (fair odds +100) and Book B has Team B at -105 (fair odds +100), you've found a scalping opportunity (bet both sides and profit from mispricing).