How to Calculate Sample Standard Deviation with STDEV.S

Measure how much values vary around the average with STDEV.S — the right choice when your data is a sample.

You will learn to

• Calculate a sample standard deviation
• Set a 3-sigma control limit
• Compare variability for one group

How it works

Standard deviation measures how far values typically sit from their average, in the same units as the data. A small standard deviation means consistent results; a large one means scattered results. =STDEV.S(C2:C11) treats the data as a sample and divides by n − 1, which corrects for the fact that a sample usually underestimates the true spread.

Use STDEV.S whenever your data is a sample of something bigger — bags pulled off a production line, survey respondents, a few weeks of sales. Use STDEV.P only when you have every member of the group you care about.

=STDEV.S(C2:C11)