📐 Standard Deviation of the Sample Mean Calculator
Calculate the standard deviation of the sample mean (also called the standard error of the mean) from your standard deviation and sample size.
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What this measures
The standard deviation of the sample mean, more commonly called the standard error of the mean (SEM), describes how much sample means would be expected to vary from the true population mean if you repeated the sampling process many times.
The formula
SEM = σ / √n, where σ is the standard deviation of the individual data values and n is the sample size. As sample size increases, the standard error shrinks, meaning larger samples give a more precise estimate of the population mean.
This calculator is intended for general statistics education and planning purposes.
Last reviewed August 2026