Math · NUMORA
Confidence Interval Calculator
x̄ ± z·σ/√n.
Open interactive calculatorHow to use
A mean confidence interval. z is 1.96 or 1.645.
Formula
half-width = z σ / √n
FAQ
Is this Confidence Interval calculator accurate?
The formula and assumptions are shown on the page, and the engine is covered by audit tests. Results are for reference — not financial or medical advice.
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What inputs do I need?
A mean confidence interval. z is 1.96 or 1.645.
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