How to calculate a weighted average
- Put one value and its weight on each line, such as 85 30% or 92 4. Spaces, commas or tabs work between them.
- Weights can be percentages, credits or counts; they don’t need to add up to 100.
- Read the weighted average and the table of value × weight.
Example
| Assessment | Score | Weight | Score × weight |
|---|---|---|---|
| Homework | 92 | 20% | 18.4 |
| Midterm | 78 | 30% | 23.4 |
| Final | 85 | 50% | 42.5 |
| Total | 100% | 84.3 |
The weighted average is 84.3, while the plain average of the three scores is 85.
Other uses
Weighted averages are behind GPA (grades weighted by credits), the average price paid when buying a share at different prices (weighted by quantity), and survey results adjusted so each group counts in proportion to its size.