Average of percentages calculator
When percentages come from groups of different sizes, a plain average misleads. Enter each percentage with its group size.
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How to use it
- Enter percentage 1, group 1 size, percentage 2, group 2 size, percentage 3 (optional) and group 3 size.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Weighted average = sum of (percentage × count) ÷ sum of counts
Example
Inputs: Percentage 1 = 80 %, Group 1 size = 50, Percentage 2 = 60 %, Group 2 size = 150. Result: Weighted average: 65%; Plain average: 70%; Total count: 200.
Limits and caveats
- You need the size of each group. When groups are equal, both averages match.
- Takes up to 4 percentages at a time.
Questions about this tool
Why not add the percentages and divide by how many there are?
That gives a small group the same weight as a large one. A pass rate of 80% of 50 students and 60% of 150 students is 65% overall, not 70%.
When is the plain average correct?
When every group is the same size; then both averages are equal.
Can I use it for grades weighted by credit hours?
Yes. If the grades are percentages, enter the credit hours as the group sizes.