Statistics

Confidence Interval Calculator

Turn a sample mean, standard deviation and size into a confidence interval at any level — with margin of error and critical value included.

Formula: CI = x̄ ± z* × (s ÷ √n). Uses the normal approximation (large samples).
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🎯 Any level

90%, 95%, 98% and 99% confidence levels.

📈 Visual band

See the interval plotted around the sample mean.

⚙ Margin of error

Know exactly how much the sample mean may vary.

⚡ Instant

Critical values handled automatically.

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