Sample Size Calculator
Calculate sample size — sample size for surveys and polls.
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Sample Size
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Minimum Sample
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What Is Sample Size?
Sample Size estimates the sample size needed for a survey given confidence level, margin of error, and proportion.
Formula
n = z² × p(1−p) / E²Frequently Asked Questions
What confidence level should I use?
95% is standard for most surveys. 99% gives wider intervals and requires larger samples.