Provide the homeschool child with his grades. To calculate GPA, every letter grade is given a numerical value that is used to convert overall grades into one number.
Add together the numerical value of each grade the homeschooled child has earned. The GPA conversion chart is as follows:
A = 4 points
B = 3 points
C = 2 points
D = 1 point
F= 0 points
Divide the total numerical value of the homeschooled child's grades by the number of classes he took. For example, if the student had seven homeschool classes and had four "A" grades and three "B" grades, the total numerical value is 25. Divide 25 by seven for a GPA of 3.57.