Standard Deviation Calculator
Measures how spread out a list of numbers is.
Result
- Sample standard deviation
- 7.6267
- Variance
- 58.1667
- Mean
- 17.1667
How to use the standard deviation calculator
- Enter the numbers (separated by commas).
- The results update as you type, or press Calculate.
- Read the sample standard deviation first, then the supporting figures below it.
Formula
s = √(Σ(x − x̄)² ÷ (n − 1)).
Worked example
For example, with these inputs:
- Numbers (separated by commas): 12, 15, 9, 22, 15, 30
the calculator returns:
- Sample standard deviation: 7.6267
- Variance: 58.1667
- Mean: 17.1667
Background
Rounding is a common source of small errors. Keep full precision during intermediate steps and round only the final answer to the number of decimal places or significant figures the question asks for.
These calculations appear throughout the Singapore syllabus, from primary school percentages and fractions to secondary school algebra and geometry. Understanding the formula makes problem sums easier because you can recognise which quantity is missing.
Frequently asked questions
How does the standard deviation calculator work?
It applies this formula: s = √(Σ(x − x̄)² ÷ (n − 1)).
Can I use any units?
Yes, as long as every input uses the same unit. The answer will be in that unit (squared for areas, cubed for volumes).