Why do people calculate GPA's differently?

Question

This is how my school calculates our GPA's (I'll use my report card grades as an example):

89x3 = 3.0x3

94 = 4.0

92 = 4.0

96 = 4.0

98 = 4.0

99 = 4.0

add the 4's and 3's all up, divide by 8, and it's 3.625

This is how my school calculates our GPA's, but why do I see people doing this differently? Is my school's way incorrect?

Answer 1

If your highest possible grade is 4.0, then it's correct.  Where the cut-offs are is up to the individual high school, but by definition the highest grade is a 4.0.  Some schools weight AP and even honors courses to give the students an incentive to take more difficult classes, but the weighting doesn't factor into their official GPA on a 4.0 scale.