Average Percentage Calculator
Test scores of 72%, 85%, and 90% average out to 82.33%. This average percentage calculator handles both the simple case, where every percentage counts equally, and the weighted case, where each percentage represents a different group size. That second case is where most percentage averaging goes wrong, because a 90% result from 10 people should not count as much as a 60% result from 500.
Quick answer
For percentages of equal standing, add them up and divide by the count.
Average percentage
82.3333%
Values counted
3
Weighted
No
What this tells you
- •For percentages of equal standing, add them up and divide by the count.
- •When percentages come from groups of different sizes, weight each one by its group size.
- •A simple average of 90% and 60% is 75%, but if the 60% covers ten times the people, the true combined rate is closer to 62.7%.
- •Weights can be sample sizes, credit hours, dollar amounts, or anything that measures how much each percentage represents.
How to Use
- 1Enter your percentages separated by commas, like 72, 85, 90.
- 2For a weighted average, enter matching weights in the same order, like 20, 30, 50.
- 3Leave the weights field empty to average everything equally.
- 4Read the average percentage, along with how many values it covers.
How It Works
Formula
weighted average = (p1 x w1 + p2 x w2 + ...) / (w1 + w2 + ...)Multiply each percentage by its weight, add the products, and divide by the total weight. With equal weights this collapses to the simple average, the sum divided by the count. For scores of 72, 85, and 90 with equal weights, the sum 247 divided by 3 gives 82.33%.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Three test scores
The three scores sum to 247, and 247 / 3 = 82.33.
Conversion rates from different traffic volumes
The 60% rate covers ten times the visitors, so the combined rate lands near it, not at the midpoint 75%.
Course grade from weighted assessments
The final exam at 50% weight pulls the course grade toward its 85%.
Simple vs Weighted Average
How weights move the average of 90% and 60%.
| Weight on 90% | Weight on 60% | Average |
|---|---|---|
| 1 | 1 | 75% |
| 1 | 2 | 70% |
| 1 | 5 | 65% |
| 1 | 10 | 62.73% |
| 10 | 1 | 87.27% |
Common mistakes
- Averaging percentages from different group sizes without weights. Combining a 90% rate from 50 users and a 60% rate from 500 as 75% overstates the true combined rate by 12 points.
- Adding percentages of different bases as if they stack. 50% of your budget plus 30% of your salary cannot be averaged into anything meaningful.
- Averaging sequential percentage changes. Growth of +10% then -10% does not average to 0%, since the second change applies to a different base.