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Power Analysis Calculator

Calculate approximate two-sided power for a one-sample mean using a standardized effect size, sample size and significance level.

Research & Data AnalysisFree calculatorGlobal reference

Calculator

Enter the values below. Every quantity identifies its unit or meaning.
Cohen's d
participants
%
Formula / method
Approximation uses the normal distribution with noncentrality d√n.

How to use this calculator

What to enter

Enter or select the following as requested: Standardized effect size (d); Sample size; Significance level (α). Follow the units, valid ranges, examples, and options displayed beside each field.

What the result means

The statistical result depends on the sample sizes, observed values, variability, confidence level, effect size, and assumptions selected. Check independence, sampling method, distribution assumptions, and whether the inputs represent the same population and measurement scale.

When to use it

Use this to plan or interpret a statistical analysis. Treat the output in the context of the study design and data quality; it does not remove bias from a non-representative sample.