How this calculator works
An equal average gives each percentage one vote. A pooled percentage gives each underlying observation one vote, so group sizes act as weights. Use pooling only when the percentages describe compatible outcomes. If the input percentages were rounded, the pooled result remains an estimate of the original combined rate.
Formula
Equal mean = Σpᵢ/k. Pooled percentage = Σ(nᵢpᵢ)/Σnᵢ, with pᵢ expressed consistently as percentages.
Worked example
A 20% result from 30 observations and an 80% result from 10 observations represent about 6 + 8 = 14 successes out of 40. The pooled rate is 35%; the simple mean of the two rates is 50%.
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Frequently asked questions
When is the simple average appropriate?
Use it when all denominators are equal or when you deliberately want to give every group equal importance.
Can I average a discount and a test score?
The arithmetic is possible but usually has no useful interpretation. Rates should refer to compatible quantities and a clear common question.
Do rounded percentages recover an exact success count?
No. A displayed percentage may conceal rounding. Use original numerator and denominator counts when an exact combined rate matters.