MATH · FREE TOOL
Standard deviation calculator
Calculate mean, variance and population or sample standard deviation.
Your inputs
Enter your values, then calculate.
Decimal-point numbers; displayed rounding does not change internal values. Calculations stay on this device.
YOUR RESULT
Make the numbers clear.
Save calculation JSON ↓Calculation breakdown
Scroll sideways to see every column. You can also focus the table and use the arrow keys.
How this calculation works
Welford’s stable online accumulation avoids the naive difference-of-squares formula. Population variance divides summed squared deviations by N; sample variance uses N−1 and needs at least two values. Up to10,000 values within±1 trillion. Grouping commas are not supported; each comma separates values.
Check the assumptions
Use the stated units and conventions. This tool supports the workflow described here; it does not infer missing information or outside rules.