Statistics
Standard Deviation
What is the Standard Deviation?
Measures spread of data from the mean
This formula is widely used in statistics applications. Understanding when and how to apply it helps you interpret calculator results correctly and catch input errors before they propagate.
Formula
s = sqrt(Sum(x - mean)^2 / (n-1))
Substitute known values into the formula above. Ensure all variables use consistent units before calculating.
Worked Example
Sample std dev of 2,4,4,5,7,9 is about 2.14
Use the linked calculator below to try your own values and see step-by-step working.
When to Use This Formula
Apply the Standard Deviation when you need to measures spread of data from the mean. It is a standard reference in statistics coursework, professional practice, and our linked calculators.
Tips & Common Mistakes
- Confirm whether you need sample or population formulas.
- Report spread measures alongside averages.
- Always verify critical results independently for engineering, medical, or legal applications.
Related Calculators
Further Reading
Browse the Formula Library for related formulas, or read educational articles on our Blog.