How to Calculate Average Percentage
Averaging percentages is easy to get wrong. If the groups are different sizes, a simple average gives the wrong answer — you need a weighted average. Paste your percentages and, optionally, the size of each group.
- Weighted average percentage
- 80.5%
- Simple average (unweighted)
- 81.6667%
Steps
- Simple: (80 + 90 + 75) ÷ 3 = 81.6667%
- Weighted: (80×20 + 90×30 + 75×50) ÷ 100 = 80.5%
Worked example
Example: three classes with 80%, 90% and 75% pass rates
- Class sizes: 20, 30 and 50 students
- Simple average = (80 + 90 + 75) ÷ 3 = 81.67%
- Weighted = (80×20 + 90×30 + 75×50) ÷ 100 = 80.5%
The true overall pass rate is 80.5%, not 81.67%.
Formula
Simple average = (p₁ + p₂ + … + pₙ) ÷ n
Weighted average = Σ(pᵢ × wᵢ) ÷ Σwᵢ
Use the simple average only when every percentage is based on the same number of items (for example, tests that are each out of 100 and count equally).
Frequently asked questions
Can you average percentages?
Yes, but only with a simple mean when every percentage has the same base. Otherwise weight each one by its size.
How do I average test scores that have different point totals?
Add all points earned and divide by all points possible. 18/20 and 40/50 give 58/70 = 82.9%.
How do I calculate average percentage in Excel?
Simple: =AVERAGE(A2:A10). Weighted: =SUMPRODUCT(A2:A10,B2:B10)/SUM(B2:B10).
Last reviewed October 17, 2026 · Calculations run in your browser; nothing you enter is sent to a server.