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T test calculator

Compare sample means with an independent-sample Welch t test or a paired t test.

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Compare sample means with an independent-sample Welch t test or a paired t test.

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Formula and assumptions
Independent: t = (mean₁ − mean₂)/√(s₁²/n₁ + s₂²/n₂), with Welch–Satterthwaite degrees of freedom. Paired: apply t = mean difference/(SD of differences/√n). Assumes appropriate independent sampling or pairing and an adequate normal model. Two-sided p-values test zero mean difference; they do not measure effect importance, causality or the probability that a hypothesis is true. The significance threshold is an editable assumption, not a probability that the null hypothesis is true.
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Using T test calculator
Compare sample means with an independent-sample Welch t test or a paired t test.
Independent: t = (mean₁ − mean₂)/√(s₁²/n₁ + s₂²/n₂), with Welch–Satterthwaite degrees of freedom. Paired: apply t = mean difference/(SD of differences/√n). Assumes appropriate independent sampling or pairing and an adequate normal model. Two-sided p-values test zero mean difference; they do not measure effect importance, causality or the probability that a hypothesis is true.
Next: Confidence interval calculator
Next: A/B test calculator
A worked example
Example inputs: first sample = 1 2 3, second sample = 2 3 4, comparison = 0. t statistic = -1.22474487139.
Before you use the result
Independent: t = (mean₁ − mean₂)/√(s₁²/n₁ + s₂²/n₂), with Welch–Satterthwaite degrees of freedom. Paired: apply t = mean difference/(SD of differences/√n). Assumes appropriate independent sampling or pairing and an adequate normal model. Two-sided p-values test zero mean difference; they do not measure effect importance, causality or the probability that a hypothesis is true.
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ToolOctopus. “T test calculator.” Updated 2026-09-26. https://tooloctopus.com/t-test-calculator.
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