If you bet based on data, you should always know how high the margin (vig) charged by the bookmaker is. Vig is the hidden cost of every bet and, in the long run, the main reason why most bettors lose. In this article, we will show you how to calculate vig, why it is so important, and how to incorporate it into your own strategy.
Key Points - Vig (bookmaker's margin) is the difference between the true odds and the odds offered by the bookmaker. - Vig is the primary reason why it is very difficult to beat bookmakers in the long term. - You will learn how to easily calculate vig on any market (including examples). - Without knowing the vig, it is impossible to assess whether a bet truly has value. - Reducing vig is key to better long-term results.
What is Vig and Why Does It Exist ### Basic Explanation Vig (also called margin, overround) is the percentage markup in the odds that the bookmaker adds as their profit. In other words: the bookmaker sets odds so that they are profitable on average over the long term—regardless of the match outcome.
For example, if the true chances of winning and losing a match are 50% each, a fair odds would be 2.00 for each outcome. However, the bookmaker usually offers something like 1.91 on both teams—the difference is their vig.
How to Calculate Vig: Practical Example ### Step by Step To find out how much vig is costing you, use the following procedure:
- 1Convert odds to probabilities: Implied probability = 1/odds.
- 2Sum the probabilities of all possible outcomes.
- 3Subtract 1 (or 100% if calculating in percentages). The result is the vig.
#### Model Example: NHL Match Bookmaker offers: - Home win: odds 1.91 - Away win: odds 1.91
Calculation: - 1/1.91 = 0.5246 (52.46%) for home - 1/1.91 = 0.5246 (52.46%) for away - Sum: 52.46% + 52.46% = 104.92% - Vig = 104.92% - 100% = 4.92%
Why Vig Destroys Long-Term Profit Vig means that if you bet without an edge (without advantage), you will always end up losing in the long run. The higher the vig, the greater the average loss per bet.
Model Loss Calculation If you bet 100 CZK on odds with a 5% vig, your expected loss is 5 CZK per every 100 CZK wagered (assuming no edge).
If you find a value bet with an edge of +2%, a 5% vig will "swallow" it and you will still end up at a loss (-3%).
How Vig Affects Value Betting and CLV ### Value Bets For a bet to have true value, your estimated probability must be higher than the probability implied by the bookmaker's odds including vig.
Example: - Bookmaker offers odds of 2.05 (implied probability 48.78%). - You estimate the chance of winning at 52%. - If the vig on the market is 4%, the true fair probability corresponds to odds of 2.00 (50%). - Your edge is 52% – 50% = 2% (after subtracting vig).
CLV (Closing Line Value) If you consistently bet at odds better than the closing line (final odds before the match), it signals that you are beating the vig and have an edge. Without understanding vig, you cannot properly evaluate CLV.
Frequently Asked Questions ### How Do I Know if Vig is Low or High? Generally, vig below 3% is very low (typical for Asian exchanges). Common European bookmakers have vig around 4–7%. Some special bets (e.g., player props) can have vig of 10% or more. Always calculate vig using the method above.
Can Vig Ever Be "Bypassed"? Vig is an inherent part of the odds offered by bookmakers. The only way to "bypass" vig is to bet on exchanges where the margin is lower, or to look for arbitrage or pricing errors. Even then, some margin remains.
Does Vig Affect Bankroll Management? Yes. The higher the vig, the greater the volatility and the faster you will lose money with the same betting approach. Bankroll management strategies should account for vig—e.g., by using more conservative stake sizes.
Conclusion Vig is a subtle but crucial factor that determines every bettor's outcome. Without knowing and calculating it, talking about value bets, edge, or long-term success makes no sense. Learn to calculate vig and don’t pay bookmakers more than necessary. Betting is a game of probabilities and numbers—not impressions. Find more tips and strategies in our articles.
Remember, betting is intended only for persons over 18 years old. Bet responsibly and never risk more than you can afford to lose.