Standard Deviation Calculator Calculators
Population and sample standard deviation, variance and quartiles.
Standard Deviation Calculator is a free online tool that population and sample standard deviation, variance and quartiles. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Calculators
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- None — it just works
- Works offline
- Yes, after the first visit
About Standard Deviation Calculator
The difference between the two figures here matters more than it looks. Dividing by n gives the population standard deviation, correct when your numbers are the entire group. Dividing by n−1 gives the sample version, which corrects for the fact that a sample underestimates the spread of the population it came from — Bessel's correction.
How to use it
- Paste the text you want to run through standard deviation calculator.
- There is nothing to configure — the result updates as you type.
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
Questions
Which one should I report?
Sample (n−1) almost always, because you almost always have a sample rather than an entire population. Use the population figure only when you genuinely measured every member of the group.
How are the quartiles calculated?
By linear interpolation between the closest ranks — the same method as R's type 7 and the default in most spreadsheets. Other conventions exist and can differ by a fraction on small datasets.
Is the arithmetic exact?
It uses double-precision floating point — about 15 significant figures, far more than the inputs justify. Displayed rounding is cosmetic; the underlying numbers are not rounded between steps, so chained results do not drift.