THE FEUTEX TOOLKIT

Mean Precision Sample Size

Estimate the sample count needed for a target mean-estimation precision with known variability.

Statistics workspace● Runs in your browser

01 Your input

Known population standard deviationvalueTarget half-widthvalueNormal critical valuenumber

02 Your result

View or copy raw result data

Result data

FormulaRequired = ceil((z*sd/margin)**2); Unrounded = (z*sd/margin)**2

Sources and model references

https://www.itl.nist.gov/div898/handbook/prc/section2/prc222.htm

Worked example

Inputs

Known population standard deviation: 10 value
Target half-width: 2 value
Normal critical value: 1.96 number

Expected results

Required: 97 count
Unrounded: 96.04 count

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

Enter the labeled inputs using consistent units.
Check the stated assumptions and calculate.
Review each output and compare another input scenario.

Try this example

{
  "sd": 10,
  "margin": 2,
  "z": 1.96
}

Accuracy and scope

Known population standard deviation or planning assumption; no finite-population adjustment. Finite floating-point arithmetic; results can lose precision near singular or extreme inputs.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.