How It Works
Add together every value in the set.
Average = (Sum of all values) / (Number of values)
- Count how many values there are.
- Divide the total by the count to get the arithmetic mean.
Enter Your Numbers
1
2
3
4
5
5 values · zero is treated as real data.
Average (Mean)
5.8000
Sum divided by the number of values.
Sum
29.00
All values added together.
Count
5
How many values were used.
Range
7.00
Largest minus smallest value.
Distribution of your values
Add your numbers to see the visual breakdown.
Your data
| # | Value |
|---|---|
| 1 | 4 |
| 2 | 7 |
| 3 | 2 |
| 4 | 7 |
| 5 | 9 |
Worked Example
Find the average of 4, 7, 2, 7, and 9.
Sum
4 + 7 + 2 + 7 + 9 = 29
Count
5 values
Average
29 / 5 = 5.8
The average is 5.8, meaning a typical value in this set is close to 5.8. Note that 9 pulls the average above most of the values; a common mistake is forgetting that one large outlier can make the average unrepresentative, which is why the median is often reported alongside it.
Understanding the Arithmetic Mean
The single number that stands in for a set
The arithmetic mean answers one question: if every entry in the set were identical, what value would each have to be to keep the same total? That is why it is the default summary of a typical grade, sale, or measurement. This tool takes up to eight numbers, returns that balance point, and also shows the running total and the count so you can see precisely what fed the result.
Sum, count, divide
The mean is the sum of the values divided by how many there are. Add every number for the total, then divide by the count. Every value carries equal weight, so changing a single entry shifts the mean by exactly that entry’s share of the whole. One consequence is worth remembering: the answer always falls between the smallest and largest numbers in the set, never outside them.
Worked example
Take the default set of 4, 7, 2, 7, and 9. Adding them gives a total of 29, and there are five values. Dividing 29 by 5 produces a mean of 5.8. That figure represents a typical value for the group even though no single entry is exactly 5.8.
When one outlier hijacks the average
Because every value pulls with equal force, a single extreme entry can drag the mean far from where most of the data sits. If the result lands well away from the bulk of your numbers, suspect an outlier and check the median, which ignores how extreme the ends are. Two mechanical slips compound this: miscounting the entries, or leaving an unused placeholder of zero inside the count, which quietly lowers the result.
When a plain mean is the wrong tool
The arithmetic mean assumes every value counts the same. The moment entries carry different weights — exam components worth different percentages, or quantities of different sizes — a plain mean misrepresents the set, and a weighted average is the correct instrument. It also describes the centre alone and says nothing about spread, so pair it with the range or standard deviation whenever the data is uneven.
Where the mean earns its keep
Report-card grades, monthly sales, average temperatures, and repeated lab readings all lean on the mean to compress many figures into one. Teachers use it to summarise a class, analysts to track a trend over time. It is the usual starting point anywhere a single number must represent many — provided you remember it is only the centre of the story, not the whole of it.
Assumptions & Best Uses
- Every value is weighted equally; for weights, use a weighted average instead.
- Values are treated as a complete set (a population), not a sample estimate.
- Results are for general and educational calculation.
Limitations
- The mean is sensitive to outliers — a single extreme value can distort it.
- It does not show how spread out the data is; check the range or standard deviation too.
- Up to eight values are supported here; for larger datasets use the statistics calculator.
Frequently Asked Questions
How do I calculate an average?
Add all the numbers together to get the sum, then divide that sum by how many numbers there are. For example, the average of 4, 6, and 8 is (4 + 6 + 8) / 3 = 6.
Is the average the same as the mean?
In everyday use, "average" almost always means the arithmetic mean, which is what this calculator finds. In statistics there are other averages (median and mode), so "mean" is the precise term.
What is the difference between average and median?
The average adds everything and divides by the count, so it is affected by extreme values. The median is the middle value when the data is sorted, so it resists outliers. They can differ a lot in skewed data.
Can the average be larger than every value?
No. The arithmetic mean always lies between the smallest and largest values in the set. If your result falls outside that range, an input was entered incorrectly.
How do I handle a weighted average?
When values carry different weights (such as exam components worth different percentages), multiply each value by its weight, add those products, and divide by the total weight. Use a dedicated weighted average calculator for that.
Can I use this for grades or test scores?
Yes, for a simple unweighted average of scores. If different assignments count for different shares of the final grade, use a weighted average instead so each piece counts correctly.
Sources & References
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
- Arithmetic mean formula: sum of n values divided by nWolfram MathWorld · verified 2026-06-06
- Mean, median, and mode as measures of center with worked examplesOpenStax Introductory Statistics · verified 2026-06-06
Note
This calculator is an educational tool. For graded coursework, exams, or professional work, double-check the method and rounding against your own requirements.
Built and maintained by Calculator Matters, an independent calculator project. Method checked against published formulas and primary sources · Last reviewed 3 June 2026 · How we calculate · Found an error? corrections@calculatormatters.com