What is a T-table used for?

A T-table (also called Student's t-distribution table) is used to find critical values for statistical hypothesis testing when the sample size is small and the population standard deviation is unknown. It's essential for determining whether to reject or accept a null hypothesis in t-tests.

How do you read a T-table?

To read a T-table: 1) Find your degrees of freedom (sample size - 1) in the left column, 2) Choose your confidence level or significance level in the top row, 3) The intersection shows the critical t-value for your test. For two-tailed tests, use the appropriate column based on your alpha level divided by 2.

What are degrees of freedom in a T-table?

Degrees of freedom (df) in a T-table equals the sample size minus 1 (n-1). It represents the number of independent values that can vary in your analysis. Higher degrees of freedom result in a t-distribution that more closely resembles the normal distribution.

T Table (Student’s t Critical Values)

Find in this t table (same as t distribution table, t score table, Student’s t table) t critical value by confidence level & DF for the Student’s t distribution.

Quick answer: For a two-tailed 95% test (α = 0.05) with df = 10, the critical t is 2.228. Use the HTML tables below (values from scipy.stats.t.ppf, round half up to 3 decimals; ∞ row is the normal z critical value).

How to read: choose one-tail or two-tail α, find degrees of freedom in the left column, and read the critical t. If your |t| exceeds the table value, reject H₀ at that α. For exact p-values or non-listed df, use the t calculators on this site.

Two-tail 95%, df = 10 → t* = 2.228
Two-tail 95%, df → ∞ → t* = z* ≈ 1.960
One-tail α = 0.05, df = 20 → t* = 1.725

Two-Tailed Critical t-Values

Two-tailed critical t-values (Student’s t). Column headers are two-tail α (confidence = 1 − α). Cell = t such that P(|T| > t) = α.
df	α=0.2 80%	α=0.1 90%	α=0.05 95%	α=0.02 98%	α=0.01 99%	α=0.002 99.8%	α=0.001 99.9%
1	3.078	6.314	12.706	31.821	63.657	318.309	636.619
2	1.886	2.920	4.303	6.965	9.925	22.327	31.599
3	1.638	2.353	3.182	4.541	5.841	10.215	12.924
4	1.533	2.132	2.776	3.747	4.604	7.173	8.610
5	1.476	2.015	2.571	3.365	4.032	5.893	6.869
6	1.440	1.943	2.447	3.143	3.707	5.208	5.959
7	1.415	1.895	2.365	2.998	3.499	4.785	5.408
8	1.397	1.860	2.306	2.896	3.355	4.501	5.041
9	1.383	1.833	2.262	2.821	3.250	4.297	4.781
10	1.372	1.812	2.228	2.764	3.169	4.144	4.587
11	1.363	1.796	2.201	2.718	3.106	4.025	4.437
12	1.356	1.782	2.179	2.681	3.055	3.930	4.318
13	1.350	1.771	2.160	2.650	3.012	3.852	4.221
14	1.345	1.761	2.145	2.624	2.977	3.787	4.140
15	1.341	1.753	2.131	2.602	2.947	3.733	4.073
16	1.337	1.746	2.120	2.583	2.921	3.686	4.015
17	1.333	1.740	2.110	2.567	2.898	3.646	3.965
18	1.330	1.734	2.101	2.552	2.878	3.610	3.922
19	1.328	1.729	2.093	2.539	2.861	3.579	3.883
20	1.325	1.725	2.086	2.528	2.845	3.552	3.850
21	1.323	1.721	2.080	2.518	2.831	3.527	3.819
22	1.321	1.717	2.074	2.508	2.819	3.505	3.792
23	1.319	1.714	2.069	2.500	2.807	3.485	3.768
24	1.318	1.711	2.064	2.492	2.797	3.467	3.745
25	1.316	1.708	2.060	2.485	2.787	3.450	3.725
26	1.315	1.706	2.056	2.479	2.779	3.435	3.707
27	1.314	1.703	2.052	2.473	2.771	3.421	3.690
28	1.313	1.701	2.048	2.467	2.763	3.408	3.674
29	1.311	1.699	2.045	2.462	2.756	3.396	3.659
30	1.310	1.697	2.042	2.457	2.750	3.385	3.646
40	1.303	1.684	2.021	2.423	2.704	3.307	3.551
60	1.296	1.671	2.000	2.390	2.660	3.232	3.460
80	1.292	1.664	1.990	2.374	2.639	3.195	3.416
100	1.290	1.660	1.984	2.364	2.626	3.174	3.390
1000	1.282	1.646	1.962	2.330	2.581	3.098	3.300
z (∞)	1.282	1.645	1.960	2.326	2.576	3.090	3.291

One-Tailed Critical t-Values

One-tailed critical t-values (Student’s t). Column headers are upper-tail α. Cell = t such that P(T > t) = α.
df	α=0.1	α=0.05	α=0.025	α=0.01	α=0.005	α=0.001	α=0.0005
1	3.078	6.314	12.706	31.821	63.657	318.309	636.619
2	1.886	2.920	4.303	6.965	9.925	22.327	31.599
3	1.638	2.353	3.182	4.541	5.841	10.215	12.924
4	1.533	2.132	2.776	3.747	4.604	7.173	8.610
5	1.476	2.015	2.571	3.365	4.032	5.893	6.869
6	1.440	1.943	2.447	3.143	3.707	5.208	5.959
7	1.415	1.895	2.365	2.998	3.499	4.785	5.408
8	1.397	1.860	2.306	2.896	3.355	4.501	5.041
9	1.383	1.833	2.262	2.821	3.250	4.297	4.781
10	1.372	1.812	2.228	2.764	3.169	4.144	4.587
11	1.363	1.796	2.201	2.718	3.106	4.025	4.437
12	1.356	1.782	2.179	2.681	3.055	3.930	4.318
13	1.350	1.771	2.160	2.650	3.012	3.852	4.221
14	1.345	1.761	2.145	2.624	2.977	3.787	4.140
15	1.341	1.753	2.131	2.602	2.947	3.733	4.073
16	1.337	1.746	2.120	2.583	2.921	3.686	4.015
17	1.333	1.740	2.110	2.567	2.898	3.646	3.965
18	1.330	1.734	2.101	2.552	2.878	3.610	3.922
19	1.328	1.729	2.093	2.539	2.861	3.579	3.883
20	1.325	1.725	2.086	2.528	2.845	3.552	3.850
21	1.323	1.721	2.080	2.518	2.831	3.527	3.819
22	1.321	1.717	2.074	2.508	2.819	3.505	3.792
23	1.319	1.714	2.069	2.500	2.807	3.485	3.768
24	1.318	1.711	2.064	2.492	2.797	3.467	3.745
25	1.316	1.708	2.060	2.485	2.787	3.450	3.725
26	1.315	1.706	2.056	2.479	2.779	3.435	3.707
27	1.314	1.703	2.052	2.473	2.771	3.421	3.690
28	1.313	1.701	2.048	2.467	2.763	3.408	3.674
29	1.311	1.699	2.045	2.462	2.756	3.396	3.659
30	1.310	1.697	2.042	2.457	2.750	3.385	3.646
40	1.303	1.684	2.021	2.423	2.704	3.307	3.551
60	1.296	1.671	2.000	2.390	2.660	3.232	3.460
80	1.292	1.664	1.990	2.374	2.639	3.195	3.416
100	1.290	1.660	1.984	2.364	2.626	3.174	3.390
1000	1.282	1.646	1.962	2.330	2.581	3.098	3.300
z (∞)	1.282	1.645	1.960	2.326	2.576	3.090	3.291

Student's T distribution table showing critical t-values for confidence levels from 80% to 99.9% and degrees of freedom from 1 to 1000

>>>Click to use a T-value calculator<<<

Or use the student's t score calculator below:

Student t-Value Calculator

In order to calculate the Student T Value for any degrees of freedom and given probability. The calculator will return Student T Values for one tail (right) and two tailed probabilities. Please input degrees of freedom and probability level and then click “CALCULATE”

Degrees of freedom:

Significance level:

T-VALUE [two-tail]

+/-

T-VALUE [one-tailed]

T Table (Student’s t Critical Values)

Two-Tailed Critical t-Values

One-Tailed Critical t-Values

Student t-Value Calculator

Other calculators