Technically, you do not need to know this - and should not predict it on your college forms but it helps you to work out your standing.
An unweighted GPA marks;
A=4 points
B=3 points
C=2 points
D=1 points
below=0 points
This should be taken from GCSE and AS Level, plus A level if possible.
The number is then divided by the number of grades of which comprise it to form a GPA up to 4.0
Eg: My GCSE grades were
7 x A (inc all A* in this section) = 28
3 x B = 9
and
AS grades of
2 x C = 4
1 x B = 3
2 x A = 8
which added together = 53
then divided by the number of grades (15)
=3.53
A weighted GPA is when AP or honors courses are given extra points. Most universities use AS and A Level grades as AP (Advanced placement)/Honors courses. A general guide is that
AP/Honors (therefore AS and A Level grades):
A = 5
B = 4
C = 3
D = 2
below = 1
and therefore when added to GCSE scores, a weighted GPA will generally be higher.
Eg:
GCSE:
(A)7*4=28
(B)3*3=9
AS-Level
(A)2*5=10
(B)1*4=4
(C)2*3=6
28 + 9 + 10 + 4 + 6 = 57
divided by number of grades = 15
57/15 = 3.8
The GPA you need will depend highly on the colleges you choose to apply to.