One-sample, two-sample independent, and paired t-tests with p-values, confidence intervals, and step-by-step solutions.
Test Type
Compare a sample mean to a known/hypothesized population mean (μ₀)
Compare means of two independent groups
Group 1
Group 2
Compare before/after or matched pairs — same subjects measured twice
Enter one value per line or comma-separated. Both groups must have the same number of values.
One-Sample
t = (x̄ − μ₀) / (s / √n)
df = n − 1
Two-Sample (Welch)
t = (x̄₁−x̄₂) / √(s₁²/n₁ + s₂²/n₂)
df = Welch-Satterthwaite
Paired
t = d̄ / (sᵈ / √n)
df = n − 1
Cohen's d
Small: 0.2 · Medium: 0.5 · Large: 0.8
d = t / √n