Average (Mean) Calculator
The mean, sum, and count of a list of numbers.
Input sheet
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The average, or mean, collapses a list of numbers into a single representative value — handy for grades, expenses, measurements, or any set of readings you want to summarize.
How it works
Add the numbers and divide by how many there are.
The mean is the total shared out equally across every item. It is sensitive to outliers: one unusually large or small value pulls the mean toward it, which is why the median is sometimes preferred for skewed data.
This tool accepts numbers separated by commas or spaces and reports the mean alongside the sum and the count, so you can sanity-check the inputs at a glance.
Mean = sum of all numbers ÷ how many numbers there are
Worked examples
Averaging the list 10, 20, 35, 40. → 26.25
Sum is 105 across 4 numbers, and 105 ÷ 4 = 26.25.
Four test scores of 88, 92, 79, and 95. → 88.5
88 + 92 + 79 + 95 = 354, divided by 4 equals 88.5.
Tips & gotchas
- If a few extreme values dominate your data, report the median (middle value) too — it resists outliers the mean cannot.
- A weighted average is different: when items carry different importance, multiply each by its weight before summing and divide by the total weight.
- Double-check the count the tool reports matches how many numbers you intended — a stray comma can silently add or drop an entry.
FAQ
What is the difference between mean, median, and mode?
The mean is the sum divided by the count. The median is the middle value when sorted. The mode is the most frequent value. They agree for symmetric data and diverge for skewed data.
Can I average percentages or rates directly?
Only if each percentage covers the same-sized group. If the groups differ, you need a weighted average or you will overweight the smaller groups.
Does the order of the numbers change the mean?
No. Addition is order-independent, so the mean is the same no matter how you arrange the list.
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