Standard Deviation Calculator Measure Data Spread & Variability
Calculate standard deviation and variance instantly. Supports both sample and population calculations with 100% client-side processing for complete data privacy.
π Quick Start
Enter Your Data
Choose Sample/Population
Get Results Instantly
Data Input
Supported Data Formats:
- Comma-separated: 1.5, 2.8, 9.1, 16.2
- Space-separated: 1.5 2.8 9.1 16.2
- Newline-separated: one number per line
- Scientific notation: 1.23e-4, 5.67E+8
- Series mode: use "Group Name: value1, value2, value3" per line to compare multiple groups
- Automatically ignores text and special characters
Statistical Results
Interpretation: Enter data to see interpretation
Data Distribution
Enter data to generate box plot
Please enter at least 4 numbers above to start calculating
Box Plot Visualization
This box plot visualizes your data distribution. The box shows the interquartile range (IQR) containing the middle 50% of data. The line inside the box represents the median. Whiskers extend to show the range, and red dots indicate outliers.
Outlier Method: Tukey (1.5ΓIQR)
Box (IQR) / Legend
- Box (IQR)
- Median Line
- Whisker
- Outliers
Combined Summary
Export Results
Calculation Method
Standard deviation measures how spread out data points are from the mean. We calculate both sample and population standard deviation:
Sample Standard Deviation (s)
Uses n-1 in denominator (Bessel's correction). Use when your data is a sample from a larger population.
Population Standard Deviation (Ο)
Uses n in denominator. Use when your data represents the entire population of interest.
Learn More
Standard Deviation vs Variance: Intuition & Use Cases
Understand when to use standard deviation vs variance, with practical examples and interpretations.
How to Read a Box Plot (mistakes to avoid)
Learn to interpret box plots correctly and avoid common misunderstandings about quartiles and outliers.
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Frequently Asked Questions
When should I use sample vs population standard deviation?
Use sample standard deviation (n-1) when your data represents a sample from a larger population. Use population standard deviation (n) when you have data for the entire population of interest.
What's the difference between standard deviation and variance?
Variance is the average of squared differences from the mean. Standard deviation is the square root of variance, making it easier to interpret as it's in the same units as your original data.
How do I interpret standard deviation values?
A smaller standard deviation means data points are closer to the mean (less variability). A larger standard deviation means data points are more spread out (more variability). About 68% of data falls within 1 standard deviation of the mean in a normal distribution.
Is my data safe with this calculator?
Yes! All calculations happen in your browser. Your data never leaves your device and is not sent to any servers. The tool works completely offline.
Can I use this for large datasets?
Yes, the calculator can handle large datasets efficiently. For very large datasets (10,000+ values), you may experience slight delays, but all processing remains local and secure.
Recent Updates
Enhanced calculation accuracy
Improved numerical precision for large datasets and edge cases
Added sample data examples
Quick-start buttons for test scores, heights, and sales data