NFL Lines overlay

[vitas27]

Once upon a time I knew how to do this, but have forgotten

Looking to calculate the overlay/+EV on NFL lines. Say I've priced it at -5.5 and the line is -7.5 -120, what is my overlay? I have a line to probability conversion table

[Cookie Monster]

Lazy way:

http://www.sportsbookreview.com/betting-tools/half-point-calculator/

Not perfect, as it has not been updated for years and does not account for total. But good enough.

For your example (fair +5.5, line +7.5 +100) gives +18.24%

[vitas27]

Thanks. What I really need is the formula, something I can use in excel

[Cookie Monster]

There is not a formula, as in spread points value on NFL varies a lot. 9 is worth very little, 3 is worth ten times more. You would need a push chart.