Standard Deviation Calculator

Numbers

Accepted: integers, decimals, negatives, scientific notation (e.g., -3.5, 1.2e3).

Drag & drop .txt/.csv here, or choose a file below.

Calculation Mode

Delimiters auto-detected: comma, semicolon, space, tab, newline. Non-numeric tokens are ignored.

Standard Deviation – Quick Cheat Sheet

Mean: \bar{x} = \Sigma x / n
Population variance: \sigma^2 = \dfrac{\Sigma (x-\mu)^2}{n}; Population stdev: \sigma = \sqrt{\sigma^2}
Sample variance: s^2 = \dfrac{\Sigma (x-\bar{x})^2}{n-1}; Sample stdev: s = \sqrt{s^2}
Computational form (used here for speed/accuracy):
\sigma^2 \text{ or } s^2 \propto \Sigma x^2 - (\Sigma x)^2 / n with denominator n (population) or n-1 (sample).
When to use which: Use population if you have the entire group; use sample if your data is a subset.
Tips: Remove outliers thoughtfully; ensure consistent units; document your choice of sample vs population.

Edge cases & notes

If n < 2 in sample mode, standard deviation is undefined (division by zero); we’ll show an error.
Non-numeric tokens (e.g., empty cells, text headers) are ignored. Scientific notation like 1.2e3 is accepted.
Rounding shown is for display only; internal math uses full precision.