Cookie preferences
We use cookies for analytics. Privacy Policy You can accept or decline non-essential tracking.
> Calculate the required audience size.
> Standard Evan Miller formula.
Calculate the required sample size for your A/B test. Based on Evan Miller's formula. Privacy-first, no signup, free for commercial use.
Explore the most common scenarios for Sample Size Calc below. Each page is a focused calculator with worked examples and edge-case guidance.
Calculate the correct sample size for your A/B test. Get statistically valid results by computing required visitors per variant with confidence and power settings.
Calculate Sample SizeCalculate how many survey responses you need for statistically valid results. Set your confidence level, margin of error, and population size.
Calculate Survey SizeCalculate sample sizes for clinical trials and medical research. Compute required participants for hypothesis testing with correct alpha and beta.
Calculate Clinical SampleCalculate statistically valid sample sizes for population studies. Set confidence interval, margin of error, and population size for research accuracy.
Calculate Statistical SampleA/B Test
Statistical significance (Z-test) and confidence intervals.
ROAS Calculator
Calculate return on ad spend, break-even ROAS, CPA, CPC, and margin-aware paid acquisition thresholds.
ROI Calculator
Ad spend ROI and unit economics calculator.
UTM Builder
Marketing link constructor with validation and presets.