Standard Deviation Calculator
Calculate the mean, variance, and standard deviation of a list of numbers. Population or sample. Free and private, right in your browser.
Paste in a list of numbers and instantly get the mean, variance, and both sample and population standard deviation, useful for checking grades, lab results, sports stats, or any dataset without opening a spreadsheet.
How to use it
- Paste or type your numbers, separated by commas, spaces, or new lines
- Choose sample or population if you need just one (both are calculated either way)
- Read off the mean, variance, and standard deviation instantly
Frequently asked questions
- Does this calculate population or sample standard deviation?
- Both are shown side by side, since they differ slightly (sample deviation divides by n-1, population divides by n). Use sample if your numbers are a subset of a larger group; use population if they're the entire dataset.
- How should I enter my numbers?
- Paste them separated by commas, spaces, or line breaks. The tool parses whatever format you drop in and ignores stray text or blank lines.
- Why does my variance look so much bigger than the standard deviation?
- Variance is the standard deviation squared, so it's in squared units (e.g. squared dollars). Standard deviation converts it back to the original units, which is why it's usually the more readable number.
- 1
Nothing is uploaded
The file never leaves your device. There is no server to send it to, so there is nothing to leak, log, or subpoena.
- 2
No signup, no limits
No account, no email, no daily cap, no watermark, and no paid tier waiting behind the third file.
- 3
Works offline
Load the page once and it keeps working with the network off, because all the work was always happening locally.