Home › Glossary › Margin
General

Margin

The percentage above 100% that the implied probabilities of all outcomes in a market add up to. A market with odds that imply 103% total probability has a 3% margin. Lower margins mean fairer odds for bettors. Also called the overround or book percentage.

Related General Terms

Odds
A numerical representation of the likelihood of an outcome and the potential return on a bet. Odds can be displayed in decimal (2.50), fractional (3/2), or American (+150) format. Higher odds indicate a less likely outcome but a larger potential payout.
Handicap
A virtual advantage or disadvantage applied to a team or player to level the playing field in a sporting event. For example, a -1.5 goal handicap means the team must win by 2 or more goals for the bet to win. Handicaps are used to create more balanced betting markets.
Stake
The amount of money a bettor risks on a single wager. Proper stake sizing is a critical component of bankroll management. Most professional bettors recommend risking between 1% and 5% of your total bankroll on any single bet to minimize the risk of ruin.
Square
A recreational or casual bettor who tends to bet based on gut feelings, popular opinion, or fan loyalty rather than statistical analysis. Squares typically bet favorites and overs, and their action is welcomed by bookmakers. The opposite of a sharp bettor.
Chalk
A slang term for the favorite in a betting market. 'Playing the chalk' means betting on favorites. The term originated from the days when odds were written in chalk on blackboards. Heavy chalk refers to a strong favorite with very low odds.
Punter
A common British and Australian term for a person who places bets, particularly on horse racing and sports. In the US, the equivalent term is typically 'bettor' or 'gambler'. The term is used casually and does not imply any particular skill level.
← Back to Glossary