How the weighted average calculator works
Last updated 10 November 2026
A simple average treats every mark alike. A weighted average lets a big module count for more than a small one.
How it works
- Weighted average = the sum of (mark × weight) ÷ the sum of the weights.
Worked example
With the starting figures:
- Three modules with weights totalling 40 give a weighted average of 66.4%.
Why weights matter
A simple average treats every mark alike. A weighted average lets a big module count for more than a small one. If a four-credit module and a sixteen-credit module have the same mark, a simple average treats them as equal, while a weighted average gives the larger module more influence.
What to enter
- The mark for each item, as a percentage or on any scale
- The weight of each item, such as its credits, its percentage of the course or its hours
- Use the same kind of weight for every row
How it is worked out
The weighted average is the sum of each mark multiplied by its weight, divided by the sum of the weights. The weights do not have to add up to a hundred. The calculator divides by their total, so credits, hours or percentages all work.
Common uses
- A year mark from tests and assignments with different weights
- An average across modules with different credits
- A course mark that combines coursework and an exam
- Any situation where some items matter more than others
Where your institution decides
Your institution may round, weight or exclude some marks differently, and it decides your official marks. Use this tool to understand how an average comes about. For marks out of different totals, see the grade calculator. Nothing you enter is saved.
A worked idea
Two marks, eighty for a module with three credits and sixty for one with twelve, give a plain average of seventy. The weighted average is much closer to sixty, because the larger module counts four times as much. That is why the weights matter, and why the answer differs from a plain average.
Things to watch
- Use the same kind of weight for every row.
- Your institution may round or weight differently.
Your institution’s own rules always decide your marks. Read the full disclaimer.