Standard Deviation Calculator
The industry-standard calculator providing instant precision, visual distribution analysis, and AI-powered interpretations for your statistical needs.
Use when your data represents a subset of a larger population. Applies Bessel's correction.
No Data Detected
Input your numbers into the Standard Deviation Calculator panel to see real-time statistics, variance, and normal distribution charts.
500K+
Users
10M+
Calculations
100%
100% Precision
99.9%
99.9% Uptime
Free
Free
What is Standard Deviation?
Standard deviation measures how spread out numbers are from their average (mean). A low standard deviation means data points are close to the mean; a high standard deviation means they're spread over a wide range.
For example, if test scores have a mean of 75 with a standard deviation of 5, most scores fall between 70-80. If the SD is 15, scores vary more widely from 60-90.
More Tools
Finance
Measure portfolio volatility and calculate risk metrics like Sharpe ratio.
Science
Validate experimental results and report measurement uncertainty.
Manufacturing
Quality control with Six Sigma and process capability analysis.
Common Questions
What if my standard deviation is zero?
All your values are identical—there's no variation in the data.
Which mode should I use?
Use Sample (n-1) for subsets, Population (N) for complete datasets.
How accurate is this calculator?
We use IEEE 754 double-precision with 15-17 significant digits.
Is my data stored?
No. All calculations happen locally in your browser.
What's the difference from variance?
Standard deviation is the square root of variance, in the same units as your data.
Ready to Analyze Your Data?
Join 500,000+ users who trust us for accurate statistical calculations. Free, fast, and no signup required.
Start Calculating