Quick example
Find the average of 12, 18, 21, 9, and 15
Add the five values to get 75, then divide by 5. The arithmetic mean is 15. Once sorted as 9, 12, 15, 18, 21, the middle value is also 15, so the median is 15.
Summary statistics
What each result means
Mean
The sum of every value divided by the count. This is what “average” most commonly means.
Median
The middle sorted value. With an even count, it is the mean of the two middle values.
Minimum and maximum
The smallest and largest values in the list, including negative numbers when present.
Range
The maximum minus the minimum. It shows the full span but not how values are distributed inside it.
Choosing a center
Mean versus median
The mean uses every value and can move sharply when a list contains an unusually large or small observation. The median depends only on the middle position, so it is often less affected by outliers. Neither is automatically better: choose the measure that describes the question and data appropriately.
Input and precision
Plain lists with equal weight
Separate values with commas, whitespace, tabs, or line breaks. Scientific notation such as 1.5e3 is accepted. Every value has equal weight, and repeating a number counts as another observation. The calculator uses compensated summation to reduce common floating-point addition error, then formats long results for readability.
Common questions
Average calculator FAQ
How do I calculate the average?
Add all values and divide the sum by the number of values. This arithmetic average is also called the mean.
What is the difference between mean and median?
The mean is sum divided by count. The median is the middle sorted value, or the average of the two middle values when the count is even.
How can I separate numbers?
Use commas, spaces, tabs, or line breaks. Negative values, decimals, and scientific notation are supported.
Does this calculator support weighted averages?
No. Every value has equal weight. Repeat a value for repeated observations, but use a dedicated weighted-average tool when weights differ.