Use this calculator when you want a spread measure in the same unit as the original data rather than only the average value.
Inputs
This topic also has a deeper guide and a printable reference pack, so you can move from the live answer into the method, assumptions, and worked examples without leaving the topic cluster.
A fuller printable guide to descriptive statistics, centre measures, spread measures, and interpretation habits that help prevent misleading summaries.
A stronger spread reference sheet for variance, standard deviation, range, and z-scores, with interpretation guidance.
These are the main values the calculator uses. Keep the units consistent and, where relevant, match the assumptions explained in the related guide.
Choose the option that matches the setup you want to analyse.
Use this page when the question is about consistency or variability rather than only the centre of the dataset.
The main result shows the spread in the same unit as the original data, which usually makes it easier to interpret than variance on its own.
Two datasets can share the same mean and still have different standard deviations. The dataset with the larger standard deviation is the one with the wider spread.
Standard deviation is most useful when the mean is already a sensible summary of the dataset. If the data is highly unusual, inspect the raw values alongside the result.
Because standard deviation is expressed in the same unit as the original data, while variance is expressed in squared units.
Use the Variance Calculator to calculate variance from your own dataset with practical output and sensible validation.
Calculate the arithmetic mean of a list of numbers when you want a quick measure of the dataset's average value.
Calculate how far a value sits from the dataset mean in standard-deviation units.
Use the Range Calculator to calculate range from your own dataset with practical output and sensible validation.