AllEasyToolsMathematics
Mean confidence interval (Z)
Mean confidence interval (Z): calculate from your inputs and inspect the formula. No account required. Processing stays in your browser.
IC = mean ± z·σ/√n
Normal interval with known σ and an independent sample. 1.96 corresponds to about 95%. Does not replace a t interval when σ is estimated.
How to use this calculator
- Identify the quantities and convert them to the units shown.
- Apply the formula first, then compare with the substitution and result.
- Check the assumptions and whether the order of magnitude makes sense.
Levels are approximate topic groupings, not a complete curriculum for every country. Numerical results are rounded and may lose precision for extreme or nearly singular inputs.
A practical example
Use these sample inputs to check the calculation before entering your own values.
- Sample mean
- 100
- Known population deviation σ
- 15
- Sample size
- 100
- Critical Z value
- 1.96
Result for this example
- Lower bound
- 97.06
- Upper bound
- 102.94
- Margin
- 2.94