Vig / Margin Calculator
Reveal the hidden bookmaker margin in any betting market. See fair odds, true probabilities, and exactly how much edge the bookmaker has built into the odds.
Low Margin (Pinnacle)
H: 2.04 | D: 3.55 | A: 3.90
Average Margin
H: 2.50 | D: 3.25 | A: 2.87
High Margin
H: 1.80 | D: 3.00 | A: 3.80
What is Bookmaker Margin?
The margin (or vig/juice) is the percentage the bookmaker builds into odds above 100% implied probability. A 5% margin means the total implied probability is 105%.
What are Fair Odds?
Fair odds are what the odds would be without any bookmaker margin. Compare fair odds to actual odds to see exactly how much value the bookmaker is taking.
What is Bookmaker Vig (Margin)?
The vig (short for vigorish), also called juice, margin, or overround, is the built-in advantage that bookmakers add to their odds. In a perfectly fair market, the implied probabilities of all outcomes would sum to exactly 100%. In practice, bookmakers inflate these probabilities beyond 100% — the excess is their profit margin.
For example, in a coin toss (50/50), fair odds would be 2.00 for both sides. But a bookmaker might offer 1.91 on each, giving a total implied probability of 104.7%. That 4.7% is the bookmaker's margin — their guaranteed edge regardless of the outcome.
Understanding the vig is crucial for profitable betting. By knowing the true fair odds, you can identify when a bookmaker's price still offers value even after accounting for their margin.
How to Use the Vig Calculator
Step 1: Select Market Type
Choose between a 3-way market (e.g., football match result: Home/Draw/Away) or a 2-way market (e.g., tennis match winner, over/under goals).
Step 2: Enter the Odds
Input the decimal odds from your bookmaker for each possible outcome. Use our Odds Converter if you need to convert from fractional or American formats.
Step 3: Analyse the Results
The calculator instantly shows the bookmaker's margin, the total overround, and the fair odds for each outcome. Compare these to what the bookmaker is offering.
Understanding the Results
Bookmaker Margin
The percentage above 100% that the total implied probabilities sum to. Lower is better for bettors — competitive bookmakers typically have 2-4% margins.
Implied Probability
The probability suggested by the bookmaker's odds (including their margin). Calculated as 1 / odds. These always sum to more than 100%.
True Probability
The estimated real probability after removing the margin. Calculated by proportionally scaling implied probabilities to sum to exactly 100%.
Fair Odds
The odds that would exist without any bookmaker margin. Fair odds are always higher than bookmaker odds.
Typical Bookmaker Margins by Market
Premier League Match Result: 3-6%
Top-tier football matches have the most competitive odds due to high liquidity.
Lower League Football: 6-10%
Less popular leagues see wider margins as bookmakers compensate for less accurate pricing.
2-Way Markets (Tennis/NBA): 3-5%
Fewer outcomes generally means lower margins than 3-way markets.
Correct Score / Exotic Markets: 15-30%
Markets with many outcomes carry the highest margins — be cautious.
Frequently Asked Questions
What is the vig in sports betting?
The vig (vigorish) is the commission bookmakers charge on every bet, built into the odds. It ensures the bookmaker profits regardless of the outcome. Also called juice, margin, or overround.
How is bookmaker margin calculated?
Sum the implied probability of each outcome (1 / decimal odds), then subtract 100%. For example, odds of 1.91 / 1.91 give 52.36% + 52.36% = 104.72%. The margin is 4.72%.
What is a good bookmaker margin?
For major football matches, margins below 4% are good, below 2% is excellent. Anything above 8% means you're getting poor value.
Why do fair odds matter?
Fair odds represent the true value of a bet. If you believe an outcome is more likely than the fair odds suggest, the bet has positive expected value.
Do all bookmakers have the same margin?
No — margins vary significantly. Sharp bookmakers (Pinnacle) offer 1-3% margins, while high-street bookmakers offer 5-10%. Always compare.
How can I reduce the impact of vig?
Shop for the best odds across multiple bookmakers, use betting exchanges, focus on major markets, and always compare prices before placing a bet.
What is overround in betting?
Overround is the total implied probability when it exceeds 100%. An overround of 105% means the bookmaker has a 5% margin.
Is the margin the same for every outcome?
Not necessarily. Bookmakers often apply more margin to one outcome than others. This calculator uses the proportional method, which is a good approximation for most markets.