A soda bottling plant claims each can holds 12 ounces, but your sample of 30 cans averages 11.8 — is the machine underfilling, or is that just random wobble? The one-sample t-test answers exactly this: it compares a sample's average against a known or claimed value and tells you whether the gap is statistically meaningful. Small samples get special handling through the t-distribution, which has fatter tails than the normal curve to reflect the extra uncertainty.

The test produces a t-statistic — the gap between your sample mean and the claimed value, measured in standard errors — and from it a p-value. A tiny p-value (below your significance level, often 5%) says the gap is too big to be chance, so you reject the claim. Quality engineers, drug-dosage checkers, and pollsters validating census figures all run this test weekly.

This calculator performs the core arithmetic of the comparison. Enter your sample's summary value in Variable A and the claimed or target value in Variable B, and the Result box combines them — the first step toward the t-statistic that decides whether the difference is real.

With the pre-filled defaults — Variable A 10, Variable B 5 — the One Sample T Test Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.