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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.

Right-Tailed T Critical Value

right tailed t critical value

Left-Tailed T Critical Value

left tailed t critical value

Two-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:

Name of TypeFormula of t critical value
Right-tailedQt,d(1 - α)
Left-tailedQt,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.

DFA = 0.10.050.0250.010.0050.0010.0005
ta= 1.2821.6451.9602.3262.5763.0913.291
13.0786.31412.70631.82163.656318.289636.578
21.8862.9204.3036.9659.92522.32831.600
31.6382.3533.1824.5415.84110.21412.924
41.5332.1322.7763.7474.6047.1738.610
51.4762.0152.5713.3654.0325.8946.869
61.4401.9432.4473.1433.7075.2085.959
71.4151.8952.3652.9983.4994.7855.408
81.3971.8602.3062.8963.3554.5015.041
91.3831.8332.2622.8213.2504.2974.781
101.3721.8122.2282.7643.1694.1444.587
111.3631.7962.2012.7183.1064.0254.437
121.3561.7822.1792.6813.0553.9304.318
131.3501.7712.1602.6503.0123.8524.221
141.3451.7612.1452.6242.9773.7874.140
151.3411.7532.1312.6022.9473.7334.073
161.3371.7462.1202.5832.9213.6864.015
171.3331.7402.1102.5672.8983.6463.965
181.3301.7342.1012.5522.8783.6103.922
191.3281.7292.0932.5392.8613.5793.883
201.3251.7252.0862.5282.8453.5523.850
211.3231.7212.0802.5182.8313.5273.819
221.3211.7172.0742.5082.8193.5053.792
231.3191.7142.0692.5002.8073.4853.768
241.3181.7112.0642.4922.7973.4673.745
251.3161.7082.0602.4852.7873.4503.725
261.3151.7062.0562.4792.7793.4353.707
271.3141.7032.0522.4732.7713.4213.689
281.3131.7012.0482.4672.7633.4083.674
291.3111.6992.0452.4622.7563.3963.660
301.3101.6972.0422.4572.7503.3853.646
601.2961.6712.0002.3902.6603.2323.460
1201.2891.6581.9802.3582.6173.1603.373
10001.2821.6461.9622.3302.5813.0983.300

T-Distribution Table (Two Tail)

Here is the t table for two-tailed probability.

DFA = 0.20.100.050.020.010.0020.001
ta = 1.2821.6451.9602.3262.5763.0913.291
13.0786.31412.70631.82163.656318.289636.578
21.8862.9204.3036.9659.92522.32831.600
31.6382.3533.1824.5415.84110.21412.924
41.5332.1322.7763.7474.6047.1738.610
51.4762.0152.5713.3654.0325.8946.869
61.4401.9432.4473.1433.7075.2085.959
71.4151.8952.3652.9983.4994.7855.408
81.3971.8602.3062.8963.3554.5015.041
91.3831.8332.2622.8213.2504.2974.781
101.3721.8122.2282.7643.1694.1444.587
111.3631.7962.2012.7183.1064.0254.437
121.3561.7822.1792.6813.0553.9304.318
131.3501.7712.1602.6503.0123.8524.221
141.3451.7612.1452.6242.9773.7874.140
151.3411.7532.1312.6022.9473.7334.073
161.3371.7462.1202.5832.9213.6864.015
171.3331.7402.1102.5672.8983.6463.965
181.3301.7342.1012.5522.8783.6103.922
191.3281.7292.0932.5392.8613.5793.883
201.3251.7252.0862.5282.8453.5523.850
211.3231.7212.0802.5182.8313.5273.819
221.3211.7172.0742.5082.8193.5053.792
231.3191.7142.0692.5002.8073.4853.768
241.3181.7112.0642.4922.7973.4673.745
251.3161.7082.0602.4852.7873.4503.725
261.3151.7062.0562.4792.7793.4353.707
271.3141.7032.0522.4732.7713.4213.689
281.3131.7012.0482.4672.7633.4083.674
291.3111.6992.0452.4622.7563.3963.660
301.3101.6972.0422.4572.7503.3853.646
601.2961.6712.0002.3902.6603.2323.460
1201.2891.6581.9802.3582.6173.1603.373
1.2821.6451.9602.3262.5763.0913.291
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