Skuti Science Free scientific calculators & converters

Confidence Interval Calculator

Confidence interval for a mean using Student's t (or z) from sample mean, standard deviation and sample size.

Results

Lower boundβ€”
Upper boundβ€”
Margin of errorβ€”
Standard errorβ€”
Critical tβ€”
Critical zβ€”

How to use the Confidence Interval Calculator

  1. Enter or select: Sample mean xΜ„, Sample std. deviation s, Sample size n, Confidence level.
  2. The results (Lower bound, Upper bound, Margin of error, Standard error, Critical t, Critical z) are calculated instantly as you type.
  3. Use β€œCopy link” to share the calculation with the same input values.

Formula

  • CI = xΜ„ Β± t(Ξ±/2, nβˆ’1) Β· s/√n

About this tool

Uses the t distribution with n βˆ’ 1 degrees of freedom, which is correct for small samples and converges to z for large n.