The term 2,5 goals is used because you are betting on one of the following:
- 2 goals or less being scored (The Under 2,5 goals market)
- 3 goals or more being scored (The Over 2.5 goals market)
The number 2,5 is used because it falls in the middle of both markets.
You either think a game will be a low scoring one with 2 goals or less or you think there will be goals a-plenty, with 3 goals or more.
If you bet on less than 2,5 goals and the game finishes 0-0, 1-0, 0-1 or 1-1 then your bet is a winner.
Yet if bet on less than 2,5 goals and the game finishes 2-1 or higher, then your bet is a loser.
And as the number of goals on average in a football game hovers around the 2,5 marker (although this varies based on trends, leagues and time of year) then its the usual market on offer.