Statistics & Probability

Instant, private, and free

Grouped Data Standard Deviation Calculator.

Calculate this statistic instantly with validated formulas.

On-device calculationNo signup
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Set your values

Results update as you type.

Result: Grouped mean: 2.222222 Population SD: 0.785674

Result

Grouped mean: 2.222222 Population SD: 0.785674

Use Cases

Analyze grouped exam scores

Teachers can enter class midpoints of score ranges to quickly find the standard deviation, helping understand score variability.

Example: Enter 45, 55, 65, 75, 85 for midpoints of score ranges.

Quality control in manufacturing

Engineers can input grouped measurements (e.g., product dimensions) to assess consistency and variability in production.

Example: Enter 10.2, 10.5, 10.8, 11.1 for grouped size ranges.

Frequently Asked Questions

How do I enter grouped data for standard deviation?
Enter the values (e.g., midpoints or class marks) separated by commas or spaces. The calculator treats each entry as a data point and computes the standard deviation using the formula for grouped data.
What formula does this calculator use?
It uses the standard formula for grouped data standard deviation: sqrt(Σ(f*(x - mean)^2) / (N - 1)) for sample, or /N for population, depending on the selected option. The calculator applies validated formulas to ensure accuracy.
Can I use this for frequency distribution tables?
Yes, if you have class midpoints and frequencies, you can enter the midpoints as values. However, this calculator does not accept separate frequency inputs; it assumes each value appears once. For frequency data, you may need to repeat values or use a dedicated frequency calculator.

Tips & Common Mistakes

Tips

  • Ensure all values are numeric and separated by commas or spaces. Avoid extra characters like semicolons.
  • For grouped data, use class midpoints as representative values for each group.
  • Decide whether you need sample or population standard deviation; the calculator may offer both options.
  • Double-check your data entry for typos, as errors can significantly affect the result.

Common Mistakes to Avoid

  • Entering frequencies along with values, but the calculator expects only the values themselves.
  • Using commas and spaces inconsistently, like '1,2 3' which may cause parsing errors.
  • Confusing sample and population standard deviation; using the wrong one can lead to incorrect conclusions.

Last updated: August 13, 2026