How to use this calculator
Enter the values shown and apply the formula Margin = z × σ / √n.
The method
Enter your values in the labeled fields and choose Calculate. The result panel shows the answer and supporting values when useful.
Sample mean: 50, Known standard deviation: 10, Sample size: 100, Critical z value: 1.96
Select Calculate to evaluate these example values.
Scope and limitations
This is a z-interval and assumes the supplied standard deviation and critical z value are appropriate for your analysis.
Common questions
Can I change the example values?
Yes. Replace every prefilled value with your own inputs and calculate again.
Are displayed results exact?
Some results are rounded for readability. Keep extra precision when the next step depends on the result.
Methods & verification
Formulas use standard mathematical definitions and fixed unit factors where applicable. See our methodology for numerical conventions, rounding, privacy, and limitations.