Average Percentage Calculator
Calculate the weighted average percentage from multiple groups with different sample sizes — the mathematically correct way to average percentages.
Enter percentages and sample sizes
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Weighted average percentage
Frequently asked questions
Why can't I just average the percentages directly? ›
Simple averaging treats all groups equally regardless of size. If Class A had 10 students scoring 90% and Class B had 100 students scoring 50%, the simple average gives 70% — but the true average is about 54%, because 100 students dominated the result. Weighted averaging accounts for group size.
What is the weighted average percentage formula? ›
Weighted Average % = (P₁×N₁ + P₂×N₂ + … + Pₖ×Nₖ) ÷ (N₁ + N₂ + … + Nₖ), where P is each percentage and N is each sample size. You can think of it as the total count of "successes" divided by the total count of observations.
When should I use simple average vs weighted average? ›
Use weighted average when the groups have different sizes and you want the overall rate across the entire population. Use simple average only when each percentage comes from the same or equivalent sample sizes, or when you're treating each group as equally important regardless of size.
About this calculator
Averaging percentages correctly requires weighting by sample size. This calculator computes the true weighted average: multiply each percentage by its group size, sum those products, then divide by total sample size. Use it for test score averages across classes, survey response rates across groups, or any scenario combining percentages from differently-sized populations.