Mean, SD & SEM Calculator
Mean, standard deviation, standard error, median, quartiles and CI from raw data.
Enter your values to see the result.
SD is the sample standard deviation (n − 1). SEM = SD ÷ √n, and the confidence interval of the mean uses the t distribution with n − 1 degrees of freedom.
Continue your work
- SD, SE & CI Converter — Convert between SD, SE and CI from summary data.
- Normality Checker — Check whether the mean and SD suit your data.
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Clear instructions
Find steps, examples and limitations below.
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How to use the Mean, SD & SEM Calculator
Mean, standard deviation, standard error, median, quartiles and CI from raw data.
- 1 Paste your values from a spreadsheet column, or type them separated by commas or spaces.
- 2 Choose the confidence level for the interval of the mean.
- 3 Copy the statistics, or the ready-made reporting sentence.
Example and practical tips
Ten readings averaging 13.53 with SD 1.10 have an SEM of 0.35 and a 95% confidence interval of 12.74 to 14.32.
Frequently asked questions
What is the difference between SD and SEM?
SD describes how spread out the data are. SEM describes how precisely the mean is estimated, and it shrinks as the sample grows.
Which should I report?
Report SD to describe your sample and a confidence interval to show the precision of the mean. Avoid using SEM just because it looks smaller.
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