a = (((Comp/Att) * 100) -30) / 20
b = ((TDs/Att) * 100) / 5
c = (9.5 - ((Int/Att) * 100)) / 4
d = ((Yards/Att) - 3) / 4
a, b, c and d can not be greater than 2.375 or less than zero.
QB Rating = (a + b + c + d) / .06
where
ATT = Number of passing attempts
COMP = Number of completions
YARDS = Passing yards
TD = Touchdown passes
INT = Interceptions