Mean, Median or Mode: Which Average Should You Use?
How to calculate each average, why outliers change the answer, and a quick guide to choosing the right one.
Mean, median and mode are three ways to describe the middle of a data set. They often give different answers, and picking the right one changes what the numbers say. Take the data set 4, 8, 15, 16, 23, 42, 8.
Mean
Add the values and divide by how many there are. The sum is 116 and there are 7 values, so the mean is 116 ÷ 7 ≈ 16.57.
Median
Sort the values and take the middle one: 4, 8, 8, 15, 16, 23, 42. The median is 15. With an even number of values, average the two middle ones. For 3, 7, 9, 12 the median is (7 + 9) ÷ 2 = 8.
Mode
The mode is the most common value. Here 8 appears twice, so the mode is 8. A data set can have no mode, if nothing repeats, or several modes.
Why outliers matter
Five people earn 30k, 32k, 35k, 38k and 300k a year. The mean is 435k ÷ 5 = 87k, but four of the five earn far less than that. The median, 35k, describes a typical person much better. This is why reports on income and house prices usually quote the median.
Which one to use
| Situation | Best average |
|---|---|
| Data is roughly symmetric, no extreme values | Mean |
| Data is skewed or has outliers | Median |
| Categories, such as shoe sizes or favorite colors | Mode |
| You need the most common single value | Mode |
Describing the spread
An average alone hides how spread out the data is. The range is the largest value minus the smallest: 42 − 4 = 38 for our data. The standard deviation measures how far values typically sit from the mean, and the calculator below shows both, step by step.
Try it: Mean, Median, Mode & Standard Deviation CalculatorMean, median, mode, range, quartiles, variance and standard deviation of a data setOpen →Frequently asked questions
Can the mean and median be the same?
Yes. In symmetric data such as 2, 4, 6, both the mean and median are 4.
When people say "average", which one do they mean?
Usually the mean. If the data has outliers, it is worth checking the median too.
Can a data set have two modes?
Yes. 1, 2, 2, 3, 3 has two modes, 2 and 3, and is called bimodal.