Average Calculator
Enter your numbers below to instantly get the average.
How to Calculate an Average
Average = sum of all values ÷ number of values.
The average is sensitive to outliers in a way the median isn't. Add one extreme value to a data set and the average shifts noticeably, while the median often barely moves — which is why income statistics are usually reported as medians, not averages.
Worked example
Data set: 4, 8, 15, 16, 23, 42.
Sum: 4 + 8 + 15 + 16 + 23 + 42 = 108
Average: 108 ÷ 6 = 18
A second example, with negative numbers: −3, 5, 2, −8, 10.
Sum: −3 + 5 + 2 − 8 + 10 = 6
Average: 6 ÷ 5 = 1.2
Common mistake
Averaging two averages directly can be wrong if the groups are different sizes. If class A (10 students) averages 80 and class B (30 students) averages 90, the overall average isn't (80 + 90) ÷ 2 = 85. It's the weighted average: (10 × 80 + 30 × 90) ÷ 40 = 3,500 ÷ 40 = 87.5.
Keep going
- A plain average treats every value equally; the weighted average calculator handles the case where some values should count for more than others. Weighted Average Calculator
Frequently Asked Questions
How do you calculate an average?
Add up all the numbers in a data set, then divide by how many numbers there are. This is also called the arithmetic mean.
Is average the same as median?
No. The average (mean) is the sum divided by the count. The median is the middle value when the numbers are sorted. They can differ a lot when a data set has outliers.
What's a real-world example of using an average?
Averaging test scores, monthly expenses, or daily step counts are common examples — anywhere you want one number that represents a typical value across many data points.
What is a weighted average?
A weighted average multiplies each value by its own weight (like frequency or importance) before dividing by the total weight, instead of treating every value equally. It's used whenever some data points should count more than others.
Can you average two averages directly?
Not unless the groups are the same size. If group sizes differ, you need a weighted average of the group averages, or the result will be skewed toward the smaller group.
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