Step 1: Convert each grade to points
The 4.0 scale assigns points to letter grades. The standard U.S. mapping is: A = 4.0, A− = 3.7, B+ = 3.3, B = 3.0, B− = 2.7, C+ = 2.3, C = 2.0, C− = 1.7, D+ = 1.3, D = 1.0, D− = 0.7, F = 0. If your school gives percentages instead, convert them to the same scale (93–100 is typically an A/4.0).
Step 2: Multiply points by credit hours
Each course is worth a number of credits (often 3 or 4). Multiply the grade points by the credits to get quality points. A 4.0 in a 3-credit course gives 12 quality points.
Step 3: Divide by total credits
Add up all quality points, then divide by the total number of credit hours you took. That final number is your GPA.
GPA = Σ(grade points × credit hours) ÷ Σ(credit hours)Worked example
Example: You take four courses: A (4.0) × 3 credits = 12, B (3.0) × 4 credits = 12, A− (3.7) × 3 credits = 11.1, C+ (2.3) × 3 credits = 6.9. Total quality points = 42 over 13 credits → GPA = 42 ÷ 13 = 3.23.
Unweighted vs weighted
The calculation above is unweighted — every A is worth the same. Weighted GPAs add bonus points for honors or AP courses (often +0.5 or +1.0) before doing the same math.