The meaning of under 4.5 goals when betting is that the game must have 4 goals or less to win.
Put simply, if you backed under 4.5 goals in a football game you would win if the end result was one of the following:
0-0, 1-0, 0-1, 1-1, 2-0, 0-2, 2-1, 1-2, 2-2, 3-0, 0-3, 3-1, 1-3, 4-0, 0-4
Any other full-time result and you would lose. For example, if the game had 5 goals or more and you had backed under 4.5 goals, you would lose your bet.
Backing under 4.5 goals is quite good because it also gives you room to trade on your bets if using a betting exchange. For example, lets say the decimal odds for under 4.5 goals was 1.12, and you really think the game will be tight with very few goals.
If you backed 1.12 for £100, if the game has under 4.5 goals you would win £12 profit. However, lets just say there are no goals in the first 25 minutes as this does happen often.
Instead of risking your £100 stake, the lay odds have now dropped to 1.08. If you then layed for £100 at 1.08 you would win £4.00 if the game ended with under 4.5 goals, however you would lose absolutely nothing if the game was to start getting loads of goals and went over 4.5.
Or if you layed £103.70 at 1.08, you would win a guaranteed £3.70 no matter what happened in the game, and your original £100 is completely safe.
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