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One-Proportion z Statistic Calculator

Calculate a one-sample z statistic for an observed proportion versus a hypothesized proportion.

Reviewed/updated September 8, 2026
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What is the One-Proportion z Statistic Calculator?

Calculate a one-sample z statistic for an observed proportion versus a hypothesized proportion. ITS Research Solution keeps the interactive tool above the explanation so you can calculate first and then review the method used.

Formula or method

z = (p̂−p0) / √[p0(1−p0)/n].

How to use this tool

Enter the requested values using consistent units, run the calculation and review the main result plus any supporting values. Compare an observed proportion with a prespecified benchmark.

Interpretation and limitations

Normal approximation methods may be unsuitable with very small counts or extreme proportions. Always check source data, units, rounding and discipline-specific requirements before using a result in assessed, published, regulated or high-stakes work.

Questions

Frequently asked questions

How is this result calculated?

z = (pu0302u2212p0) / u221a[p0(1u2212p0)/n].

Can I use this result in formal academic or research work?

Use it as a transparent calculation aid, then verify the assumptions, units, rounding and any institution-, journal- or field-specific requirements before formal use.