Step-by-step working
The computation, laid out line by line so you can check every number. Calculate above to begin.
Standard Deviation Calculator
Standard deviation, variance, mean and a full step-by-step calculation for population or sample — pasted straight from a spreadsheet, stripped of blanks, and verified line by line.
The computation, laid out line by line so you can check every number. Calculate above to begin.
It is not a magic formula. It is the average distance your data sits from its own midpoint — with a story in every point.
One divides by n, the other by n−1. Getting the difference wrong quietly ruins a whole report of statistics.
The variance is the squared units, the standard deviation puts them back in your real scale. The link, shown cleanly.
Draw any normal-ish set and roughly 68% of points sit inside one deviation. What that means for a measured sample.
A narrow spread means reliability; a wide one means variety. How to read the size of a standard deviation before you crunch it.