T Test Calculator
One-sample and two-sample t statistics.
Enter your values
ⓘ Live results
Results
- t statistic
- -4.40542
- Mean difference
- -4.1429
- Standard error
- 0.9404
- Mean 1
- 13.2857
- Mean 2
- 17.4286
- Approx. df
- 6
Quick answer
A t test measures how many standard errors separate means, telling you whether a difference is likely real.
t = (x̄ − μ) / (s/√n)
How to use the T Test Calculator
- 1Paste sample 1 values.
- 2Add sample 2 for a two-sample test, or leave blank.
- 3Enter the hypothesised mean for a one-sample test.
Worked example
Using the values the calculator loads with:
Inputs
- Sample 1 values12, 14, 11, 15, 13, 16, 12
- Sample 2 values (optional)17, 15, 19, 16, 18, 20, 17
- Hypothesised mean (one sample)13
Results
- t statistic-4.40542
- Mean difference-4.1429
- Standard error0.9404
- Mean 113.2857
- Mean 217.4286
- Approx. df6
Frequently asked questions
When do I use a t test instead of z?
When the population standard deviation is unknown and the sample is small.
What t value is significant?
Roughly 2.0 for 30 observations at the 5% level — check a t table for exact df.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.