T-Value Calculator

Calculate t-statistic and p-value for t-tests. Free online t-test calculator.

The T-Value Calculator computes t-statistics and p-values for hypothesis testing when population standard deviation is unknown. Enter sample data to perform one-sample or two-sample t-tests. Essential for comparing means, evaluating differences, and conducting statistical inference with small to moderate samples.

Common use cases

  • Comparing sample mean to population
  • A/B testing significance
  • Medical treatment comparison
  • Educational intervention assessment
  • Quality improvement analysis

How to use

  1. Select one-sample or two-sample test
  2. Enter sample statistics (mean, SD, n)
  3. Enter hypothesized value or second sample
  4. Click calculate for t-statistic
  5. View p-value and interpretation

FAQ

What is a t-test?

A hypothesis test for means when population standard deviation is unknown, using sample standard deviation.

What is the t-statistic?

t = (x̄ - μ₀)/(s/√n) for one-sample, measuring how far sample mean is from hypothesized mean in standard errors.

How many degrees of freedom?

For one-sample: n-1. For two-sample independent: various formulas, often n₁+n₂-2 for pooled variance.

When is t-test appropriate?

For approximately normal data or large samples (n>30), when comparing means with unknown population SD.