How to use
- Enter all numbers in one box—paste from Excel or type with commas or line breaks.
- To replace the whole set, select all and paste; use Add for one extra value.
- Pick sample (n−1) or population (n); results update instantly.
Formulas
Sample variance divides by n − 1; population variance divides by n.
What standard deviation tells you
Low SD means values cluster near the mean; high SD means spread. Two classes with the same average test score can differ sharply in SD if one has many outliers.
Example: small class scores
Scores 88, 90, 91, 94, 97 → mean 92, sample SD near 3.5. Scores 70, 85, 92, 100, 113 → same mean possible with much larger SD.
Population vs sample
Use sample SD when your list is a subset (survey respondents). Use population SD when the list is the entire group (all employees in a 10-person shop).
How do I calculate standard deviation online?
Enter your data (paste or one box per number), choose sample or population, and read SD on the right.
Sample vs population standard deviation?
Sample when the list is a subset (survey); population when it is the entire group.
Same as Excel STDEV?
Sample mode matches STDEV.S; population matches STDEV.P for the same numbers.
How many numbers do I need?
Population SD needs at least 1 value; sample SD needs at least 2.
Standard deviation vs variance?
Variance is SD squared. This page shows SD; square the result if you need variance.
Paste from Excel or Sheets?
Yes—copy a column and paste into the bulk box; commas or line breaks both work.
Add one more value?
Use Add one number below the main box—it appends to your list.
Weighted standard deviation?
Not supported—enter each raw measurement only.