Confidence Interval Tool

Confidence Interval Calculator

Sample size (amount), n

Sample size must be at least 2

Sample Mean (average), X̄

Please enter a valid number

Standard Deviation, σ or s

Standard deviation must be positive

Confidence Level

Sample Mean (X̄):

Margin of Error:

Confidence Interval:

Confidence Level:

Formula used:
CI = X̄ ± z*(σ/√n)
Where:
X̄ = sample mean
z = z-score for confidence level
σ = population standard deviation
n = sample size

Accurate Confidence Interval Calculator