The first thing to understand is that all prices have an implied probability equivalent. For -3 -111 the -3 is the point spread and the -111 is the price. To calculate the implied probability we need to use the formula risk/return=implied probability. To be clear return includes both stake plus win, so for example at -111 a bet of $111 to win $100 has a return of $211 (stake+win). In this example 111/211= 0.5261 which changed to a percentage is 52.61%. This means when betting at -111 you’ll need to win 52.61% of the time to break even and this 52.61% is referred to as the implied probability.
Let’s examine -3 -111 moved to -2.5. All that’s change here is we win instead of push when the favorite wins by exactly three. To calculate the -2.5 equivalent we need to determine exactly how often teams favored by -3 win by exactly 3 points. Using a combination of historical results data and no-vig lines at sharp betting sites I determined this happens about 9.80% of the time. I just calculated one paragraph up that -111 has a 52.61% equivalent. If I add half 9.8% I get an implied probability of 57.51%. I can now go to an odds converter plug in 57.51% in the implied probability field and see in American odds format this is -135. Therefore -3 -111 and -2.5 -135 have the same expected win/loss.
Why did I use only half of 9.8%? If we were moving from -3.5 to -2.5 I could have used the full 9.8% probability of 3 as we’d of picked up all of that probability. The reason I couldn’t do this is because we were moving from a push to a win (I also would use half when moving from a loss to a push). You see that 9.8% is built half into our line of -3 and half in the opposite team’s line of +3 and for this reason we can only take half the probability.
The first thing to understand is not all half points are created equal. For example the push probability of 3 is about 9.8% and the push probability of 7 is about 5.72%. These are the two most common margins of victory. Meanwhile -9 only pushes 0.9% of the time, and -12 about 0.44% of the time. Many online sportsbooks sell half points involving the 7 for 15 cents, half point involving the 3 for 25 cents and all other half points at 10 cents each. Under this cost per half point pricing there are only sixteen scenarios where purchasing half points is a better bet than passing on the option to do so.
When to Purchase Two Half Points
Let’s examine -3 -111 moved to -2.5. All that’s change here is we win instead of push when the favorite wins by exactly three. To calculate the -2.5 equivalent we need to determine exactly how often teams favored by -3 win by exactly 3 points. Using a combination of historical results data and no-vig lines at sharp betting sites I determined this happens about 9.80% of the time. I just calculated one paragraph up that -111 has a 52.61% equivalent. If I add half 9.8% I get an implied probability of 57.51%. I can now go to an odds converter plug in 57.51% in the implied probability field and see in American odds format this is -135. Therefore -3 -111 and -2.5 -135 have the same expected win/loss.
Why did I use only half of 9.8%? If we were moving from -3.5 to -2.5 I could have used the full 9.8% probability of 3 as we’d of picked up all of that probability. The reason I couldn’t do this is because we were moving from a push to a win (I also would use half when moving from a loss to a push). You see that 9.8% is built half into our line of -3 and half in the opposite team’s line of +3 and for this reason we can only take half the probability.
The first thing to understand is not all half points are created equal. For example the push probability of 3 is about 9.8% and the push probability of 7 is about 5.72%. These are the two most common margins of victory. Meanwhile -9 only pushes 0.9% of the time, and -12 about 0.44% of the time. Many online sportsbooks sell half points involving the 7 for 15 cents, half point involving the 3 for 25 cents and all other half points at 10 cents each. Under this cost per half point pricing there are only sixteen scenarios where purchasing half points is a better bet than passing on the option to do so.
When to Purchase Two Half Points
- -3.5 purchase to -2.5 by purchasing two half points for 50 cents
- +2.5 purchase to +3.5 by purchasing two half points 50 cents
- -10.5 purchase to -9.5 by purchasing two half points 20 cents
- +9.5 purchase to +10.5 by purchasing two half points 20 cents
- -14.5 purchase to -13.5 by purchasing two half points 20 cents
- +13.5 purchase to +14.5 by purchasing two half points 20 cents
- -17.5 purchase to -16.5 by purchasing two half points 20 cents
- +16.5 purchase to +17.5 by purchasing two half points 20 cents
- -3 to -2.5 by purchasing one half points for 25 cents
- +3 to +3.5 by purchasing one half points 25 cents
- -10 purchase to -9.5 by purchasing one half points 10 cents
- +10 purchase to +10.5 by purchasing one half points 10 cents
- -14 purchase to -13.5 by purchasing one half points 10 cents
- +14 purchase to +14.5 by purchasing one half points 10 cents
- -17 purchase to -16.5 by purchasing one half points 10 cents
- +17 purchase to +17.5 by purchasing one half points 10 cents
