Average Calculator
Calculate the average (arithmetic mean) of any list of numbers instantly. Paste numbers separated by commas, spaces, or new lines — get the average, sum, and count as you type.
5 valid numbers detected
Average
20
Sum
100
Count
5
Min – Max
12 – 30
The average (arithmetic mean) is the sum of every value divided by how many values there are. Non-numeric entries are ignored automatically, so you can paste messy data directly from a spreadsheet or document.
What Is an Average?
The average — technically the "arithmetic mean" — is a single number that summarizes a whole set of values. It's found by adding every value together and dividing by how many values there are, which gives a sense of the "typical" or "central" value in the set without having to look at every individual number.
Averages show up everywhere — average test scores, average temperatures, average spending, average response times — because they compress a list of numbers into one comparable figure.
Average Formula
Average = Sum of Values ÷ Number of ValuesAdd every number in the set together to get the sum, count how many numbers are in the set, then divide the sum by that count. The order the numbers are listed in doesn't matter — the sum (and therefore the average) comes out the same regardless of order.
How to Calculate the Average
- 1List every number in the data set.
- 2Add all the numbers together to get the sum.
- 3Count how many numbers are in the set.
- 4Divide the sum by the count.
Worked Example
Find the average of 12, 18, 25, 30, and 15.
- Sum: 12 + 18 + 25 + 30 + 15 = 100
- Count: 5 numbers
- Average: 100 ÷ 5 = 20
These are the calculator's default values above — edit the list to see the result update instantly.
Average vs. Median vs. Mode
These three are all called "measures of central tendency," but they're calculated differently and can give very different answers on the same data set:
- AAverage (mean): sum of all values ÷ count of values. Every value affects the result, so it's sensitive to outliers.
- MMedian: the middle value once the data is sorted (or the average of the two middle values, for an even count). Not affected by extreme outliers.
- OMode: the value that appears most often in the set. The only one of the three that also works on non-numeric (categorical) data.
Common Mistakes & Edge Cases
- Treating the average as the same thing as the medianThe average (mean) adds every value and divides by the count; the median is the middle value when the data is sorted. They agree for symmetric data but diverge sharply with skewed data — e.g. the average of 1, 2, 3, 4, 100 is 22, while the median is 3. Reporting one when the other was asked for is one of the most common statistics mistakes.
- A single outlier can dominate a small averageBecause every value is weighted equally in the sum, one unusually large or small number pulls the average toward it — the smaller the data set, the bigger the pull. If a data set has an extreme outlier, consider reporting the median alongside the average, or checking whether the outlier is a data-entry error before including it.
- Averaging a set of averagesThe average of several sub-group averages is only correct if every sub-group has the same number of data points. If group sizes differ, averaging the group averages directly overweights the smaller groups — the correct approach is to go back to the raw totals (sum of all values ÷ total count) rather than averaging the already-averaged numbers.