If every percentage comes from the same total, add them and divide by how many there are. If the totals differ, use a weighted average: multiply each percentage by its total, add the results and divide by the sum of the totals. 80% of 50 and 90% of 150 average to 87.5%, not 85%.
Formulas
simple average = (p₁ + p₂ + … + pₙ) ÷ nweighted average = (p₁ × n₁ + p₂ × n₂ + …) ÷ (n₁ + n₂ + …) Examples
- Three tests marked out of 100: 72%, 85% and 90% average to 82.33%.
- A class of 20 with 60% passing and a class of 30 with 80% passing: (60 × 20 + 80 × 30) ÷ 50 = 72% overall.
Common mistakes
- Using a simple average for groups of different sizes. Leave the totals empty only when every group is the same size.
- Averaging percentage changes over time. For growth over several periods, multiply the factors instead.
In Excel and Google Sheets
- Percentages in A2:A10
=AVERAGE(A2:A10) - Weighted by totals in B2:B10
=SUMPRODUCT(A2:A10,B2:B10)/SUM(B2:B10)
FAQ
When should I use a weighted average?
Whenever the percentages come from different totals, such as tests worth different points or groups of different sizes.
How do I average marks from tests with different totals?
Enter each percentage with its total here, or add up the marks and divide by the total possible with the marks percentage calculator.
Can I average percentage increases?
Not with a simple average. +10% and then −10% is −1% overall: multiply 1.10 × 0.90 = 0.99 instead.
How we calculate: exact decimal math (no rounding errors), you choose the decimal places, and your numbers never leave your browser. Methodology →
Updated October 2026