Mean Calculator
Find the arithmetic mean (average) of a set of numbers.
What the Mean Calculator does
The arithmetic mean adds every value and divides by how many there are. It is the standard average, though it can be dragged by outliers — the median is often a better summary of skewed data.
Formula
Mean = (Σx) ÷ n
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Numbers | text | Yes | Separate values with commas, spaces or new lines. |
How to use it
- Enter Numbers.
- Select Calculate.
Worked example
Test scores of 78, 85, 92, 67 and 88.
- Numbers
- 78, 85, 92, 67, 88
Sum 410 ÷ 5 = 82 average.
Reading the result
- The mean is the balance point of the data — the deviations above and below it cancel exactly.
- It responds to every value, so one extreme figure shifts it. Comparing it against the median shows whether the data is skewed.
Common mistakes
- Averaging a set of averages without weighting each by how many values it covered.
- Using the mean on long-tailed data such as incomes, where the median describes a typical case far better.
Frequently asked questions
When is the mean misleading?
When the data is skewed or has extreme outliers. One billionaire in a room lifts the mean income far above what anyone actually earns; the median stays honest.