The number of tails: We need to know whether our t-test is one-tailed or two-tailed because we will use the respective one-tail or two-tail row to mark the alpha level.The pre-requisites required to using a T-table are: Next, we are going to learn how to read the T-Table and map critical values on it using examples and diagrams but first we will need a few things or pre-requisites before we can do that. The T Table given below contains both one-tailed T-distribution and two-tailed T-distribution, df up to 1000 and a confidence level up to 99.9%įree Usage Disclaimer: Feel free to use and share the above images of T-Table as long as you provide attribution to our site by crediting a link to How to Use the T-Table Given below is the T Table (also known as T-Distribution Tables or Student’s T-Table).