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Confidence Interval for a Mean (t-Distribution) Calculator

CI = x̄ ± t_(α/2, n-1) · s / √n — small-sample CI.

Compute the confidence interval for a population mean using the t-distribution (sample standard deviation, df = n − 1): CI = x̄ ± t · s / √n. Provide your own t critical value (e.g. 2.262 for 95 % with 9 df).

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

CI = x̄ ± t · s / √n

In depth

Compute the confidence interval for a population mean using the t-distribution (sample standard deviation, df = n − 1): CI = x̄ ± t · s / √n. Provide your own t critical value (e.g. 2.262 for 95 % with 9 df).