T-Test Calculator

Perform one-sample and two-sample t-tests with t-statistic and p-value.

t-Statistic

3.0945

Significant?

Yes (p<0.05)

T-Test Results

t-Statistic3.0945
Degrees of Freedom58
p-value (approx)0.0119
Mean Difference3.2000

Use the T-Test Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

The T-Test Calculator determines if there's a significant difference between the means of two groups. It's crucial for research and data analysis to validate hypotheses, such as comparing the effectiveness of two different treatments or examining if a new process improves outcomes.

This calculator typically uses either the independent samples t-test (for two unrelated groups) or the paired samples t-test (for related groups). It calculates a t-statistic using the difference between means, divided by the standard error of the difference, and then determines a p-value to assess statistical significance.

Ensure your data meets the assumptions of the t-test (e.g., normal distribution, equal variances for independent samples). A common mistake is misinterpreting a statistically significant result as a large practical effect; always consider effect size alongside the p-value.

Example: Comparing Test Scores After Two Teaching Methods

  1. 1 A teacher wants to see if a new teaching method improves student scores. Group A (control) used the old method, and Group B (experimental) used the new method. Input the test scores for each group into the calculator.
  2. 2 The calculator processes the scores for Group A and Group B, calculating their respective means, standard deviations, and the t-statistic. It then determines the p-value associated with this t-statistic.
  3. 3 The calculator outputs a t-statistic of, say, 2.5 and a p-value of 0.015. This p-value is below the common significance level of 0.05.
  4. 4 Since the p-value (0.015) is less than 0.05, we reject the null hypothesis. This suggests there is a statistically significant difference in test scores between the two teaching methods, indicating the new method likely had an effect.

Source: Khan Academy · Last updated: April 2026

Frequently Asked Questions

When should I use a t-test instead of a z-test?
Use a t-test when the sample size is small (typically under 30) or the population standard deviation is unknown (which is most real-world situations). The t-distribution accounts for the extra uncertainty from estimating the standard deviation from the sample.
What is the difference between a one-sample and two-sample t-test?
A one-sample t-test compares a sample mean to a known or hypothesized value (is this group different from 100?). A two-sample t-test compares the means of two independent groups (is group A different from group B?).
What does degrees of freedom mean in a t-test?
Degrees of freedom (df) represent the number of independent values that can vary. For a one-sample t-test, df = n - 1. For a two-sample t-test, df depends on whether you assume equal variances. More degrees of freedom make the t-distribution closer to a normal distribution.

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