How to Calculate a Weighted Average (Formula + Example)
Short answer
A weighted average multiplies each value by its weight, adds those products, then divides by the total of the weights. Check your work with our average calculator.
Course grades, investment returns and survey scores often use weights so some items count more than others. A plain average treats every number equally; a weighted average does not.
Weighted average formula
Weighted average = (v1×w1 + v2×w2 + … + vn×wn) ÷ (w1 + w2 + … + wn). Weights can be percentages that add to 100, or raw points.
Worked example: class grade
Homework 80% with weight 20, midterm 70% with weight 30, final 90% with weight 50.
Products: 80×20 = 1600, 70×30 = 2100, 90×50 = 4500. Sum of products = 8200. Sum of weights = 100. Weighted average = 82%.
| Component | Score | Weight | Score × weight |
|---|---|---|---|
| Homework | 80 | 20 | 1600 |
| Midterm | 70 | 30 | 2100 |
| Final | 90 | 50 | 4500 |
| Total | 100 | 8200 |
Confirm with the average calculator, or explore grade needs with the final grade calculator and GPA calculator.
Common mistakes
- Averaging percentages that already embed different weights without using those weights.
- Forgetting to divide by the sum of weights when weights do not add to 1 or 100.
- Mixing decimal weights (0.2) with percent weights (20) in the same sum.
Last updated: 14 Oct 2026. Educational maths only. ViralScopeHub is not responsible for school or finance decisions.
Frequently asked questions
What is the difference between average and weighted average?
A simple average gives every value equal weight. A weighted average lets some values count more.
Can weights be percentages?
Yes, if they add to 100 (or you still divide by their sum).
How do I do this in a spreadsheet?
Use SUMPRODUCT of values and weights, then divide by SUM of weights.
Is GPA a weighted average?
Often yes: credit hours weight each course grade.
Where can I check my arithmetic?
Use our free average calculator and compare with your hand working.