When you look at a betting line, you aren’t seeing the true probability of an event occurring. You are seeing the probability plus the bookmaker’s fee, known as the “Vig,” “Juice,” or “Margin.”
For example, if two NFL teams are perfectly matched, the fair odds should be +100 (2.00) for both. However, sportsbooks typically offer -110 (1.91). That difference is the tax you pay to bet. Our 2-Way No-Vig Calculator strips away this fee to reveal the Fair Odds and True Win Probability. This is the first step in identifying a mathematical edge against the house.
No-Vig Calculator
Fair OddsHow to Use the No-Vig Calculator
This tool is essential for “Origination”—the process of creating your own lines to compare against the market. Here is how to use it:
- Select Market Type:
- Spread / Handicap: For betting on the point margin (e.g., Lakers -5.5).
- Over / Under: For betting on the total score (e.g., Total 220.5).
- Enter Odds for Both Sides: You must input the odds for both outcomes to calculate the margin.
- Example: If DraftKings has the Chiefs at -120 and the Ravens at +100, enter both numbers.
- Analyze the Results:
- Fair “No-Vig” Probability: This is the actual percentage chance the team has to win, according to the market’s consensus.
- Fair Odds: This is what the line would be if the bookmaker took zero profit. If you can find a sportsbook offering odds better than the “Fair Odds,” you have found a positive value (+EV) bet.
Related Tools: Once you have found a bet with an edge, use the Kelly Criterion Calculator to determine exactly how much of your bankroll to wager. To see the raw theoretical hold percentage of the bookmaker, check the Margin Calculator.
Real-World Examples: Finding the “True Price”
Why is -110 not a 50% break-even proposition? Let’s look at the math.
Example 1: The Standard Line (-110 / -110)
Most NFL spreads open with both sides at -110.
- Implied Probability (with Vig): 52.38% per side.
- Total Market Probability: 104.76% (The extra 4.76% is the Vig).
- No-Vig (Fair) Probability: 50.00%.
- Fair Odds: +100.
- Lesson: You must win 52.38% of your bets just to break even.
Example 2: The Lopsided Line (-125 / +105)
A bookmaker creates a line where the favorite is -125 and the underdog is +105.
- Favorite (-125): Fair Probability is 54.0% (Fair Odds: -117).
- Underdog (+105): Fair Probability is 46.0% (Fair Odds: +117).
- Lesson: Even though the underdog is listed at “Plus Money” (+105), the true math suggests they should be paying even more (+117). This line represents bad value on the underdog.
Frequently Asked Questions (FAQ)
What is “Push Logic”?
In 2-Way markets (like Spreads and Totals), a tie results in a “Push” (money back). When calculating probabilities, we ignore the push scenario and normalize the percentages so that Side A + Side B = 100%. This tells you: “Assuming the game does not end in a push, what is the probability of winning?”
Why do I need to enter odds for both sides?
You cannot calculate the “Vig” with only one side of the bet. The vigorous is derived from the gap between the two opposing lines. The wider the gap (e.g., -120 / -120), the higher the fee the bookmaker is charging.
What are “Fair Odds”?
Fair Odds (or True Odds) represent the break-even price of a bet with zero house edge. Professional bettors use this number as a benchmark. If you calculate the Fair Odds to be -110, but a sportsbook is offering -105, you have a mathematical advantage.