Quick start
- Enter values separated by commas, spaces, or line breaks.
- Choose Sample for a sample data set or Population for the full group.
- Press Calculate standard deviation.
- Review the answer, variance, mean, range, and steps.
Best uses
Start here if one of these sounds like your job. The examples below show which inputs matter most.
- Measure how spread out a list of numbers is from its mean.
- Compare sample standard deviation with population standard deviation.
- Check statistics homework, study data, measurements, and class examples.
- Copy the standard deviation, variance, mean, and count for notes.
Sample vs population
Use Sample when your data is only part of a larger group. Sample standard deviation divides by n - 1, which is the common classroom and survey choice.
Use Population when your list contains every value in the group. Population standard deviation divides by n.
Reading the result
A smaller standard deviation means the values are closer to the mean. A larger standard deviation means the values are more spread out.
The calculator also shows variance because standard deviation is the square root of variance.
Worked examples for Standard Deviation Calculator
Population SD = 2
Sample SD = 2.1380899353
Mean = 19.1666666667
FAQ in plain language
What does standard deviation measure?
Standard deviation measures how far data values typically are from the mean. A larger standard deviation means the values are more spread out.
Should I use sample or population standard deviation?
Use sample standard deviation when your data is a sample that estimates a larger population. Use population standard deviation when the data includes the whole group you care about.
What do the main Standard Deviation Calculator inputs mean?
The main inputs are the numbers, operation, mode, or known values the calculator needs. Keep units consistent, enter percentages the way the page label shows, and use the examples as a quick check before trusting the answer.
How should I read the Standard Deviation Calculator answer?
Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.
What should I double-check before trusting the Standard Deviation Calculator?
Check units, signs, rounding, and the selected mode before copying the answer. If the number feels weird, rerun one of the examples first, then put your own values back in slowly.
Why does sample standard deviation divide by n - 1?
Sample standard deviation divides by n - 1 to correct for estimating population spread from a sample. This is often called Bessel correction.
How many values can I enter?
You can enter up to 1,000 values separated by commas, spaces, semicolons, or new lines.
Sources
Use these if you want to compare the formula, inputs, or limits with a trusted outside explanation.
Related tools
- Statistics Calculator Calculate count, sum, mean, median, mode, range, quartiles, variance, and standard deviation.
- Mean, Median, Mode, Range Calculator Find the four headline descriptive statistics for a list of numbers.
- Z-score Calculator Calculate a z-score and approximate standard normal percentile.
Keep exploring
If this guide is close but not exact, these links keep you near the same kind of problem.
- Calculators Browse the full category for related tools that help with the same job.
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- All calculator and utility guides Find more plain-language examples, formulas, mistakes, and result explanations.
- Free calculator resources Start here when you are not sure which calculator page fits.
Privacy and copying results
Recent answers stay visible only while you work in the current browser tab. They are not sent to a server.
Use Copy answer when you want to save the inputs and result in notes, homework, a message, or a project list. Check the units, labels, and limits before copying.