How to calculate the mean
Add all the values, then divide by how many values there are. For test scores 82, 91, 77, 88 and 95 the sum is 433, there are 5 scores, so the mean is 433 ÷ 5 = 86.6.
If some values count more than others (a final exam worth 50% of the grade), use the weighted average calculator instead. For growth rates and ratios, the geometric mean is the right average.
The mean as a balance point
Picture the values as equal weights on a ruler: the mean is where it balances. That is why deviations from the mean always sum to zero, and why a single far-away value can shift the mean a lot. Compare it with the median in the mean, median, mode calculator.
Frequently asked questions
Is mean the same as average?
In everyday use, yes: “average” usually means the arithmetic mean. Strictly, median and mode are also kinds of average.
How do I find a missing value to reach a target mean?
Multiply the target mean by the total count to get the required sum, then subtract the values you already have. For a mean of 85 over 5 tests with 82, 91, 77, 88 so far: 85 × 5 − 338 = 87.
What is the symbol for mean?
x̄ (“x-bar”) for a sample mean and μ (“mu”) for a population mean.