# T Value (Critical Value) Calculator

Select the type of probability, enter the degree of freedom and significance level to calculate t value using our t value calculator.

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## 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.

## T critical value formula

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

 Name of Type Formula of t critical value Right-tailed Qt,d(1 - α) Left-tailed Qt,d (α) Two-tailed ±Qt,d (1 - α/2)

## 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.

DF A = 0.1 ∞ ta= 1.282 1.645 1.960 2.326 0.05 0.025 0.01 0.005 0.001 0.0005 3.078 6.314 12.706 31.821 63.656 318.289 636.578 1.886 2.920 4.303 6.965 9.925 22.328 31.600 1.638 2.353 3.182 4.541 5.841 10.214 12.924 1.533 2.132 2.776 3.747 4.604 7.173 8.610 1.476 2.015 2.571 3.365 4.032 5.894 6.869 1.440 1.943 2.447 3.143 3.707 5.208 5.959 1.415 1.895 2.365 2.998 3.499 4.785 5.408 1.397 1.860 2.306 2.896 3.355 4.501 5.041 1.383 1.833 2.262 2.821 3.250 4.297 4.781 1.372 1.812 2.228 2.764 3.169 4.144 4.587 1.363 1.796 2.201 2.718 3.106 4.025 4.437 1.356 1.782 2.179 2.681 3.055 3.930 4.318 1.350 1.771 2.160 2.650 3.012 3.852 4.221 1.345 1.761 2.145 2.624 2.977 3.787 4.140 1.341 1.753 2.131 2.602 2.947 3.733 4.073 1.337 1.746 2.120 2.583 2.921 3.686 4.015 1.333 1.740 2.110 2.567 2.898 3.646 3.965 1.330 1.734 2.101 2.552 2.878 3.610 3.922 1.328 1.729 2.093 2.539 2.861 3.579 3.883 1.325 1.725 2.086 2.528 2.845 3.552 3.850 1.323 1.721 2.080 2.518 2.831 3.527 3.819 1.321 1.717 2.074 2.508 2.819 3.505 3.792 1.319 1.714 2.069 2.500 2.807 3.485 3.768 1.318 1.711 2.064 2.492 2.797 3.467 3.745 1.316 1.708 2.060 2.485 2.787 3.450 3.725 1.315 1.706 2.056 2.479 2.779 3.435 3.707 1.314 1.703 2.052 2.473 2.771 3.421 3.689 1.313 1.701 2.048 2.467 2.763 3.408 3.674 1.311 1.699 2.045 2.462 2.756 3.396 3.660 1.310 1.697 2.042 2.457 2.750 3.385 3.646 1.296 1.671 2.000 2.390 2.660 3.232 3.460 1.289 1.658 1.980 2.358 2.617 3.160 3.373 1.282 1.646 1.962 2.330 2.581 3.098 3.300

## T-Distribution Table (Two Tail)

Here is the t table for two-tailed probability.

DF ∞ ta = 1.282 1.645 1.960 2.326 2.576 A = 0.2 0.10 0.05 0.02 0.01 0.002 0.001 3.078 6.314 12.706 31.821 63.656 318.289 636.578 1.886 2.920 4.303 6.965 9.925 22.328 31.600 1.638 2.353 3.182 4.541 5.841 10.214 12.924 1.533 2.132 2.776 3.747 4.604 7.173 8.610 1.476 2.015 2.571 3.365 4.032 5.894 6.869 1.440 1.943 2.447 3.143 3.707 5.208 5.959 1.415 1.895 2.365 2.998 3.499 4.785 5.408 1.397 1.860 2.306 2.896 3.355 4.501 5.041 1.383 1.833 2.262 2.821 3.250 4.297 4.781 1.372 1.812 2.228 2.764 3.169 4.144 4.587 1.363 1.796 2.201 2.718 3.106 4.025 4.437 1.356 1.782 2.179 2.681 3.055 3.930 4.318 1.350 1.771 2.160 2.650 3.012 3.852 4.221 1.345 1.761 2.145 2.624 2.977 3.787 4.140 1.341 1.753 2.131 2.602 2.947 3.733 4.073 1.337 1.746 2.120 2.583 2.921 3.686 4.015 1.333 1.740 2.110 2.567 2.898 3.646 3.965 1.330 1.734 2.101 2.552 2.878 3.610 3.922 1.328 1.729 2.093 2.539 2.861 3.579 3.883 1.325 1.725 2.086 2.528 2.845 3.552 3.850 1.323 1.721 2.080 2.518 2.831 3.527 3.819 1.321 1.717 2.074 2.508 2.819 3.505 3.792 1.319 1.714 2.069 2.500 2.807 3.485 3.768 1.318 1.711 2.064 2.492 2.797 3.467 3.745 1.316 1.708 2.060 2.485 2.787 3.450 3.725 1.315 1.706 2.056 2.479 2.779 3.435 3.707 1.314 1.703 2.052 2.473 2.771 3.421 3.689 1.313 1.701 2.048 2.467 2.763 3.408 3.674 1.311 1.699 2.045 2.462 2.756 3.396 3.660 1.310 1.697 2.042 2.457 2.750 3.385 3.646 1.296 1.671 2.000 2.390 2.660 3.232 3.460 1.289 1.658 1.980 2.358 2.617 3.160 3.373 1.282 1.645 1.960 2.326 2.576 3.091 3.291