What is the difference between sample and population standard deviation?

Population standard deviation divides by n (the count) and is used when your data covers the entire group. Sample standard deviation divides by n − 1 and is used when your data is a sample drawn from a larger population — the n − 1 correction reduces bias in the estimate.

How is standard deviation calculated?

Find the mean, subtract it from each value and square the result, sum those squared differences, divide by n (population) or n − 1 (sample) to get the variance, then take the square root to get the standard deviation.

Is my data uploaded anywhere?

No — the calculation runs entirely in your browser, and the numbers you paste are never uploaded.

Standard Deviation Calculator

Standard deviation calculator

Measure how spread out your data is. Paste a list of numbers, choose whether it is a sample (divides by n − 1) or the whole population (divides by n), and the calculator returns the standard deviation, variance and mean.

Standard deviation tells you the typical distance of each value from the mean — a small value means the data is tightly clustered, a large value means it is widely spread. Everything is computed in your browser, so nothing you enter is uploaded.