The mean, or arithmetic average, is the sum of a set of numbers divided by how many numbers there are. It is the "typical value" most people mean when they say average.
Mean = Sum of all values ÷ Number of values
On the 30-day sample below: 32.73.
When to use it
The mean uses every value, so it is the right average when totals matter: average daily orders times the number of days gives total orders exactly.
Worked example
Here the mean is pulled up a little by day 17, a one-day sale with 61 orders. When one or two values are far from the rest, compare the mean with the median before quoting it.
=AVERAGE(C2:C31)| Day | Website orders |
|---|---|
| 1 | 24 |
| 2 | 27 |
| 3 | 22 |
| 4 | 30 |
| 5 | 28 |
| 6 | 25 |
| 7 | 31 |
| 8 | 29 |
| 9 | 26 |
| 10 | 33 |
| 11 | 30 |
| 12 | 28 |
| 13 | 35 |
| 14 | 32 |
| 15 | 29 |
| 16 | 34 |
| 17 | 61 |
| 18 | 31 |
| 19 | 36 |
| 20 | 33 |
| 21 | 30 |
| 22 | 37 |
| 23 | 35 |
| 24 | 32 |
| 25 | 38 |
| 26 | 36 |
| 27 | 34 |
| 28 | 40 |
| 29 | 37 |
| 30 | 39 |
Common mistakes
- One extreme value can move the mean a long way. The median is not affected by how extreme the extremes are.
- An average of averages is not the overall average unless every group is the same size. Weight by size, or add up first.
- Blank cells are ignored by AVERAGE but zeros are not. A day with no orders recorded as blank raises the average.
Calculate it yourself
Related methods
See all statistics methods or the business metrics they are used on.
Guides that use it
- Where to find free public data, and how to check it before you trust it — 2 min read
- How to analyze your data without SQL or code — 2 min read
- Types of data analysis: descriptive, diagnostic, predictive and prescriptive — 2 min read
- How to do data analysis: 6 steps with a worked example — 4 min read
- Data analysis methods and techniques, and when to use each — 3 min read
- Excel data analysis: formulas, PivotTables and the ToolPak — 3 min read
Further reading
Questions people ask
- What is mean?
- The mean, or arithmetic average, is the sum of a set of numbers divided by how many numbers there are. It is the "typical value" most people mean when they say average.
- What is the formula for mean?
- Mean = Sum of all values ÷ Number of values. On the 30-day sample data the result is 32.73.
- How do you calculate mean in Excel?
- Use =AVERAGE(C2:C31) with the data in rows 2 to 31. The same formula works in Google Sheets.
About the data on this page
The figures come from a small made-up dataset, printed above in full so you can check every number by hand. Download it as daily.csv. The results are computed from those rows when the page is built, and the Excel formulas, SQL and Python on these pages are run against the same rows before publishing, so the code and the answers agree.
To get these numbers from your own data without writing formulas, try AnalyzeIt: ask in plain words and it shows the working behind every figure.
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