What is margin and how is it calculated in sports betting?

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Every bettor has heard the word ‘margin,’ but not everyone understands what it means. At first glance, bookmaker odds seem to be a fair reflection of the probabilities of events. However, they contain a hidden percentage that ensures the bookmaker's income regardless of the outcome. This percentage is called the margin.

What is margin? To bet successfully, it is important to understand how margin works and how it can be calculated. After all, margin directly affects the odds and, accordingly, the player's profit.

What is a bookmaker's margin?

A margin is a bookmaker's commission built into the odds. Simply put, it is the difference between the actual probability of an event and the probability offered by the bookmaker. Thanks to this, even with an even distribution of bets, the bookmaker remains in the black. The lowest commission can be found at the Mal bet bookmaker, where it does not exceed 3-4% for top tournaments. 

For example, if the probability of an event is 50%, the ‘fair’ odds should be 2.0. But the bookmaker will offer 1.90 or 1.85. This difference is the margin. At first glance, it may seem insignificant, but it is precisely this margin that gradually ‘eats away’ at the player's profit in the long run.

The margin exists in absolutely every outcome and in every market — be it football, tennis or e-sports.

Moreover, its size depends on the popularity of the event and the policy of the particular company: top matches often have a lower margin, while rare and niche tournaments have a higher one.

How to calculate the margin

The formula for calculating the margin is quite simple, although in practice it requires careful attention.

Algorithm:

1. Convert the odds into probabilities: Probability = Odds1
2. Add up the probabilities obtained for all outcomes.
3. Subtract 100% from this sum. The remaining value will be the bookmaker's margin.

Example:

A match with two outcomes.

• Odds for the first team to win: 1.90
• Odds for the second team to win: 1.90

Convert the odds into percentages:

• 1 / 1.90 ≈ 0.526 (52.6%)
• 1 / 1.90 ≈ 0.526 (52.6%)

Sum = 105.2%

Excess over 100% = 5.2% → this is the bookmaker's margin.

Thus, the player always ‘overpays’ this percentage, and the bookmaker earns.

Why it is important to consider the margin

1. Determining profitable bets. The lower the margin, the higher the player's real chances of making a profit in the long run.
2. Comparing bookmakers. Some bookmakers keep their margin at 2-3% for top matches, while others raise it to 8-10%.
3. Gaming strategies. With a low margin, long-term strategies work more effectively, while with a high margin, the risk increases.

The ability to calculate the margin allows you to soberly assess the conditions of the game and choose the bookmaker with the most advantageous offers.

Conclusion

The margin is a hidden ‘tax’ on bets that the bookmaker imposes. Its size directly affects the player's final profitability. To be successful in betting, it is important to learn to recognise it and take it into account when choosing odds and strategies. The lower the margin, the fairer the game.

Understanding this simple but important concept not only allows you to better navigate the world of betting, but also increases your chances of long-term profit.