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Free Margin of Error
Calculator

Calculate margin of error for proportions or means using z or t critical values, add finite-population correction, compare confidence levels, or recover margin from interval bounds.

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About Free Margin of Error Calculator

Calculate sampling margin of error for a proportion or a mean, choose z or t where appropriate, apply finite-population correction when sampling without replacement, or recover the margin directly from confidence-interval bounds.

Available actions

  • Proportion
  • Proportion · worst case
  • Mean · known σ
  • Mean · unknown σ
  • From CI bounds
  • Calculate margin