T Value (Critical Value) Calculator

Critical Value Calculator

T critical value calculator is an online statistical tool that calculates the t value for one-tailed and two-tailed probability. Moreover, the critical values calculator also shows the mapped t-value in the student t-distribution table for one sample and two samples.

What is the t value?

T value measures the size of the difference relative to the variation in sample data. It is basically the calculated difference represented in units of standard error.

• If the t value is greater, there is evidence of a significant difference.
• If the t-value is closer to 0, there are chances of no significant difference.

Right-Tailed T Critical Value

Left-Tailed T Critical Value

Two-Tailed T Critical Value

T critical value formula

The formulas of t critical value for left, right, and two-tailed values are:

How to find the critical value of t?

To calculate the t critical value manually (without using the t calculator), follow the example below.

Example:

Calculate the critical t value (one tail and two tails) for a significance level of 5% and 30 degrees of freedom.

Solution:

Step 1: Identify the values.

Significance level = 5% = 5/100 = 0.05

Degree of freedom = 30

Step 2: Look for the significance level in the top row of the t distribution table below (one tail) and degree of freedom (df) on the left side of the table. Get the corresponding value from a table.

T critical value (one-tailed) = 1.6978

Step 3: Repeat the above step but use the two-tailed t table below for two-tailed probability.

T critical value (two-tailed +/-) = 2.0428

Use our t table calculator above to quickly get t table values.

T-Distribution Table (One Tail)

The t table for one-tailed probability is given below.

T-Distribution Table (Two Tail)

Here is the t table for two-tailed probability.