Bookmaker margin calculator
Enter the odds for every outcome in one market, such as home, draw and away. The calculator shows the margin and the fair odds without it.
Written by BettingSeeker Editorial Team
Why margins matter
The margin is what the bookmaker keeps in the long run. Two bookmakers can offer the same team at different prices, and over hundreds of bets the one with the lower margin leaves more money in your pocket. That is why we measure margins for every bookmaker we review.
Worked example
A football match priced at 2.10 home, 3.40 draw and 3.60 away:
- Implied probabilities: 1 ÷ 2.10 = 47.62%, 1 ÷ 3.40 = 29.41%, 1 ÷ 3.60 = 27.78%
- Total: 104.81%, so the margin is 4.81%
- Fair home odds: 2.10 × 1.0481 = 2.20
The formula
Margin = (1 ÷ odds₁ + 1 ÷ odds₂ + … + 1 ÷ oddsₙ) − 1, using decimal odds. Fair odds for each outcome = odds × (1 + margin).
Frequently asked questions
What is a bookmaker margin?
It is the built-in edge in a market, also called the overround or vig. If you add up the implied probabilities of every outcome, the total is above 100%. The amount above 100% is the margin.
What is a good margin?
Lower is better for bettors. Main football markets at competitive bookmakers often carry margins of around 2–6%, while niche markets and accumulator-style bets can be much higher.
What are fair odds?
Fair odds are the prices with the margin removed. This calculator spreads the margin across outcomes in proportion to their implied probability, which is the simplest common method.