How to calculate an average
The average, or mean, is the sum of all the values divided by how many there are: average = sum ÷ count. For 10, 20, 30, 40 and 50, the sum is 150 and there are 5 numbers, so the average is 150 ÷ 5 = 30.
The mean is the balance point of the data: the distances above it exactly cancel the distances below it. That is also why every value influences the answer — change one number and the mean moves. The mean is only one measure of centre; the mean, median and mode calculator shows all three side by side.
How to use this calculator
Enter your numbers in the value fields — leave any you don't need blank, and only the filled-in ones are counted. The result shows the mean, the total sum, and how many numbers you entered.
Check the count shown in the result against how many numbers you meant to enter, and keep every value in the same unit. When some values should count for more than others, switch to the weighted average calculator.
Mean vs. median vs. mode
The mean is the arithmetic average shown here. The median is the middle value when sorted, and the mode is the most frequent value. The mean is sensitive to outliers — one very large number pulls it up — while the median is not. For spread around the mean, use the standard deviation calculator.
A practical rule: if the mean and the median sit close together, the data is roughly symmetric and the mean describes it well. If they are far apart, the data is skewed and the median is usually the fairer summary.
Frequently asked questions
- How do I calculate the average?
- Add all the numbers together, then divide by how many numbers there are. For 10, 20, 30, 40, 50: 150 ÷ 5 = 30.
- What is the difference between mean and average?
- In everyday use they're the same thing — the arithmetic mean is the common average.
- Does a blank field count?
- No. Only the fields you fill in are included in the count and the sum.
- How is the average affected by outliers?
- A single very large or very small value shifts the mean noticeably. The median is more resistant to outliers.
- Can I average percentages or rates directly?
- Usually not — a plain mean of percentages is only correct when each one covers the same size group. If the groups differ, weight each percentage by its group size first, otherwise a rate from a tiny sample counts as much as one from a huge sample.