Bookmaker margin is a small hidden percentage added by bookmakers to every betting market. It helps them make a profit, no matter who wins the game. Many bettors do not notice it, but understanding how it works is important.
What Is Bookmaker Margin?
Bookmaker margin is the extra percentage a bookmaker adds to the real chances of an event. This helps the bookmaker make sure they earn money in the long run.
For example, in a football match between two teams with equal chances of winning, the real odds should be 2.00, which mean 50% for each team to win. But the bookmaker may offer 1.90 on both sides instead. This small change means the bookmaker is building in a profit, and this is the margin.
How Bookmakers Add Margins to Odds
Bookmakers do not show the real chances. They change the odds just a little, so the total chance shown in the odds is more than 100%. This small increase gives them a safe zone to make money.
Let’s take a simple example of a football match between Team A and Team B.
Odds of Team A to win: 1.80
Odds of Team B to win : 2.00
To find out how much margin is added, bettors need to convert the odds to percentage. This helps them understand how the bookmaker sets the market.
How to Calculate Betting Margins
To calculate the bookmaker margin, bettors use a 3-step method.
- Convert each odd to a percentage
In order to convert odds to a percentage, there is the following formula
1 / decimal odds = Implied probability - Add all the probabilities together
If there are two or three outcomes, bettors add them all. - Deduct 100 from the total implied probability
The number that is show after the subtraction is the bookmaker margin.
Example
Team A odds: 1.80 – Implied Probability = 1 / 1.80 = 0.5556 = 55,56%
Team B odds: 2.00 – Implied Probability = 1 / 2.00 = 0.50 = 50%
Total implied probability = 55,56% + 50% = 105,56%
Deduction of 100 = 105,56% – 100% = 5.56%
This means the bookmaker has added a 5.56% margin to this market.
Why Is Bookmaker Margin Important?
Bookmaker margin affects how much money a bettor can win. A higher margin means lower value for the player. A lower margin means better odds and better chances of profit.
Professional players and value bettors always look at the margin before placing a bet. They try to bet in markets with smaller margins. This gives them better long-term results.
Tools to Automatically Calculate Betting Margins
Many online tools can help calculate bookmaker margin. These are called betting margin calculators. They are very simple to use. Bettors only need to enter the odds for each outcome and the calculator shows the total margin.
Some websites also show the margin directly for each match. This saves time and helps players compare which bookmaker offers better value.
Bookmaker Margin in 3-Way Markets
Some sports like football offer 3 outcomes: Team A win, Draw, Team B win. Bettors can use the same formula as above to calculate the margin of a 3-way market. In these markets, margins are often higher, so it is good to check.
Example
Team A odds: 2.50 – Implied Probability = 1 / 2.50 = 0.40 = 40%
Draw odds: 3.20 – Implied Probability = 1 / 3.20 = 0.3125 = 31.25%
Team B odds: 2.80 – Implied Probability = 1 / 2.80 = 0.3571 = 35.71%
Total Implied Probability = 40 + 31.25 + 35.71 = 106.96%
Bookmaker margin = 106.96% – 100% = 6.96%
How to Find Low-Margin Bookmakers
Some bookmakers offer low-margin odds. These are often called sharp or value bookmakers. It is important to learn how to spot them because even a small difference like 2% or 3% can make a big impact if a bettor places many bets.
Compare odds many bookmakers
Use a betting margin calculator
Choose the bookmaker with the lowest margin
In Short
Bookmaker margin is a not direct but very important part of betting. It shows how much the bookmaker is earning from each market. Knowing how to calculate the margin can help people make better choices. By using simple tools or doing a quick check by hand, bettors can find better odds and improve their chances.