Confidence Interval Calculator

Calculate confidence intervals for population mean and proportion. Supports multiple confidence levels. Free online confidence interval calculator.

Calculate CI for

Confidence Level

Sample Mean (x̄)

Standard Deviation (s)

Sample Size (n)

Mean: x̄ ± z × (s/√n)

Proportion: p̂ ± z × √(p̂(1-p̂)/n)

Where z is the critical value for the chosen confidence level

80%

1.282

85%

1.44

90%

1.645

95%

1.96

99%

2.576

99.5%

2.807

99.9%

3.291

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