Standard Deviation Calculator
Paste a list of numbers to calculate the standard deviation and variance — a measure of how spread out your data is around the mean. Choose between sample and population standard deviation.
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Enter at least one number to see a result.
Paste your dataset above to see the result.
How It Works
Standard deviation measures how spread out your values are from the mean. First, find the mean of your dataset. Then, for each value, find its squared difference from the mean and add them all up — this sum is used to calculate the variance. Sample standard deviation divides that sum by (n − 1), where n is the number of values (this is called Bessel's correction, used when your data is a sample from a larger population). Population standard deviation instead divides by n (used when your dataset IS the entire population, not a sample of it). The standard deviation is the square root of the variance in either case.
MyDelsu is an independent student platform and is not affiliated with DELSU administration. This tool is provided for guidance only — always verify results against your official transcript, result slip, or academic regulations.
Frequently Asked Questions
Population vs sample standard deviation — which should I use?+
Use sample standard deviation (dividing by n − 1) when your data is a sample drawn from a larger population — this is the more common case, e.g. survey responses from a subset of students. Use population standard deviation (dividing by n) only when your dataset already includes every member of the population you care about, e.g. the ages of every student in one specific class.
Why does sample standard deviation divide by (n − 1) instead of n?+
Dividing by (n − 1), known as Bessel's correction, corrects for the fact that a sample's mean tends to slightly underestimate the true spread of the full population — it produces a less biased estimate of the population's actual standard deviation.
What's the difference between variance and standard deviation?+
Variance is the average of the squared differences from the mean. Standard deviation is simply the square root of the variance, which brings it back into the same units as your original data (e.g. if your data is in Naira, standard deviation is in Naira, but variance is in Naira²).
Why is my standard deviation 0?+
A standard deviation of 0 means every value in your dataset is identical — there's no spread at all around the mean.
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