Average (Mean) Calculator
Find the average, sum and median of a list of numbers.
Updates as you type.
What Is an Average (Arithmetic Mean)?
The average, more precisely called the arithmetic mean, is the single value that best represents a set of numbers. You find it by adding up all the values and dividing by how many values there are. The formula is:
Mean = sum of all values ÷ number of values
Or written compactly, mean = (Σx) ÷ n, where Σx is the total of the numbers and n is the count. The average tells you what each value would be if the total were shared out equally across all the items, which is why it is so useful for summarising test scores, prices, temperatures, or any list of data into one representative figure.
Because every value contributes to the sum, the mean uses all your data — a strength when the numbers are evenly spread, but something to watch when a few extreme values are present.
How to Average a List of Numbers Step by Step
Calculating an average takes just three steps:
- Add the numbers. Find the total (sum) of every value in your list.
- Count the numbers. Note how many values you added — this is n.
- Divide. Divide the sum by the count to get the mean.
For example, to average 4, 8, 15, 16 and 23: the sum is 4 + 8 + 15 + 16 + 23 = 66, the count is 5, so the mean is 66 ÷ 5 = 13.2.
The same procedure works for any quantity of numbers, including decimals and negatives. The calculator above does all three steps instantly — just enter your values separated by commas or spaces and read off the result, along with the sum and count.
Worked Example: Averaging Exam Scores
Imagine a student earns these marks across six tests:
- Test 1: 88
- Test 2: 74
- Test 3: 91
- Test 4: 80
- Test 5: 67
- Test 6: 96
Step 1 – Add the scores: 88 + 74 + 91 + 80 + 67 + 96 = 496
Step 2 – Count the scores: there are 6 tests, so n = 6
Step 3 – Divide: Mean = 496 ÷ 6 = 82.67
The student's average score is about 82.67. If you wanted a specific final average, you could rearrange the idea: to reach an average of 85 over six tests you would need a total of 85 × 6 = 510 marks, which is 14 more than the current 496. This kind of target calculation is handy for planning the score needed on a remaining test.
Mean vs Median vs Mode
The mean is one of three common measures of central tendency, and choosing the right one matters:
- Mean — the arithmetic average; uses every value, but is pulled toward extreme outliers.
- Median — the middle value when the numbers are sorted; resistant to outliers and often better for skewed data such as incomes or house prices.
- Mode — the value that appears most often; useful for categories and repeated readings.
Consider the salaries 30, 32, 34, 36 and 200 (in thousands). The mean is 66.4, which no single person actually earns, because the 200 outlier drags it up. The median is 34, a far more typical figure. When your data contains extreme values, report the median alongside the mean so readers are not misled. For evenly distributed data, the mean and median sit close together and the average is the clearest summary.
Frequently Asked Questions
The average, or arithmetic mean, is sum of all values ÷ number of values. Add every number in your list, then divide by how many numbers there are. For example, the average of 10, 20 and 30 is (10 + 20 + 30) ÷ 3 = 20.
The mean is the sum of the values divided by their count, while the median is the middle value when the data is sorted in order. The mean uses every number and is sensitive to outliers; the median ignores extremes and better represents skewed data such as incomes or property prices.
Exactly the same way as whole numbers: add all the values, including their decimal parts, then divide by the count. For example, the average of 2.5, 3.5 and 4.0 is (2.5 + 3.5 + 4.0) ÷ 3 = 10 ÷ 3 = 3.33. The calculator handles decimals automatically.
Yes, and it usually is. The mean represents the balanced central value, so for 4 and 8 the average is 6, which appears in neither input. The average reflects the overall total shared equally, not necessarily any single value you entered.
Multiply your target average by the total number of items to get the required total, then subtract the marks you already have. For example, to average 80 over 5 tests you need 400 total marks; if you have 310 so far, the remaining test must score 90.
Because the mean adds every value, a single very large or very small number shifts the total and pulls the average toward itself. With data like 1, 2, 3 and 100, the mean of 26.5 misrepresents most of the values. In such cases the median gives a more reliable sense of the typical value.