Confidence Interval Calculator

Calculate confidence intervals for a population mean using z-distribution.

Sample Mean (x̄)

Confidence Level

Std Deviation (s)

Sample Size (n)

95% Confidence Interval[94.6323, 105.3677]

Margin of Error± 5.3677

Standard Error2.7386

Z-value for 95%± 1.96

Formulax̄ ± z × (s/√n)

SE = s / √n15 / √30 = 2.7386

Z-Values by Confidence Level

90%z = ± 1.6449

95%z = ± 1.96

99%z = ± 2.5758