Statistics & Probability Calculators
Standard Error Calculator
Compute the standard error of the mean from a standard deviation and sample size.
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What is Standard Error?
The standard error is the standard deviation of the sample mean — how much the mean would jump around if the study were repeated. It is s ÷ √n, so it shrinks with the square root of the sample size rather than in proportion to it.
How it works
The sample standard deviation is divided by the square root of n. Because the relationship is a square root, quadrupling the sample only halves the error; that consequence is stated on the page because it is what makes precision expensive.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.