There are two types of averages you often encounter: the arithmetic average and the weighted average. In this article, we explain the difference and when to use each.
An arithmetic average is the 'regular' average you know. You add up all grades and divide by the count. Each grade counts equally.
Arithmetic average = (grade1 + grade2 + ... + gradeN) / N
Example: You have a 12, 14, and 16. The average is (12 + 14 + 16) / 3 = 14/20
With a weighted average, some grades count more heavily than others. Each grade is multiplied by a weight before calculating the average.
Weighted average = Σ(grade × weight) / Σ(weight)
Example: Exam 12/20 (weight 3), test 16/20 (weight 1). Average = (12×3 + 16×1) / (3+1) = 52/4 = 13/20
The core difference is:
- Arithmetic average: All grades are equal - count the same
- Weighted average: Some grades count more - have more influence
- With equal weights, the weighted average gives the same result as the arithmetic
- All components are equally important
- Quick calculation without weights
- Temperature, speed, or other measurements
- School grades with different weights (exams vs. assignments)
- University with ECTS credits
- Investment returns or other financial calculations
Most Belgian schools use a weighted average. Exams often count more heavily than small tests or assignments.
At university, ECTS credits (study points) are used as weighting factors. A 6 ECTS course counts twice as much as a 3 ECTS course.
Always check the weights of your subjects in Smartschool or your course information!
Our calculator supports both weighted and arithmetic averages. Choose the mode that fits your situation.