AP®StatisticsCollege BoardRevision NotesCourse OverviewCourse OverviewTable for t-Distribution Critical Values

Table for t-Distribution Critical Values (College Board AP® Statistics): Revision Note

Syllabus Edition

First teaching 2026

First exams 2027

Dan Finlay

Written by: Dan Finlay

Reviewed by: Roger B

Updated on

Table B: t-distribution critical values

The table entry for tail probability p and confidence level C is the point t^{*} with probability p lying above it and probability C lying between -t^{*} and t^{*}.

Tail probability p in column header; two-sided confidence level C equivalent is shown in the row below the table.

df

.25

.20

.15

.10

.05

.025

.02

.01

.005

.0025

.001

.0005

1

1.000

1.376

1.963

3.078

6.314

12.71

15.89

31.82

63.66

127.3

318.3

636.6

2

.816

1.061

1.386

1.886

2.920

4.303

4.849

6.965

9.925

14.09

22.33

31.60

3

.765

.978

1.250

1.638

2.353

3.182

3.482

4.541

5.841

7.453

10.21

12.92

4

.741

.941

1.190

1.533

2.132

2.776

2.999

3.747

4.604

5.598

7.173

8.610

5

.727

.920

1.156

1.476

2.015

2.571

2.757

3.365

4.032

4.773

5.893

6.869

6

.718

.906

1.134

1.440

1.943

2.447

2.612

3.143

3.707

4.317

5.208

5.959

7

.711

.896

1.119

1.415

1.895

2.365

2.517

2.998

3.499

4.029

4.785

5.408

8

.706

.889

1.108

1.397

1.860

2.306

2.449

2.896

3.355

3.833

4.501

5.041

9

.703

.883

1.100

1.383

1.833

2.262

2.398

2.821

3.250

3.690

4.297

4.781

10

.700

.879

1.093

1.372

1.812

2.228

2.359

2.764

3.169

3.581

4.144

4.587

11

.697

.876

1.088

1.363

1.796

2.201

2.328

2.718

3.106

3.497

4.025

4.437

12

.695

.873

1.083

1.356

1.782

2.179

2.303

2.681

3.055

3.428

3.930

4.318

13

.694

.870

1.079

1.350

1.771

2.160

2.282

2.650

3.012

3.372

3.852

4.221

14

.692

.868

1.076

1.345

1.761

2.145

2.264

2.624

2.977

3.326

3.787

4.140

15

.691

.866

1.074

1.341

1.753

2.131

2.249

2.602

2.947

3.286

3.733

4.073

16

.690

.865

1.071

1.337

1.746

2.120

2.235

2.583

2.921

3.252

3.686

4.015

17

.689

.863

1.069

1.333

1.740

2.110

2.224

2.567

2.898

3.222

3.646

3.965

18

.688

.862

1.067

1.330

1.734

2.101

2.214

2.552

2.878

3.197

3.611

3.922

19

.688

.861

1.066

1.328

1.729

2.093

2.205

2.539

2.861

3.174

3.579

3.883

20

.687

.860

1.064

1.325

1.725

2.086

2.197

2.528

2.845

3.153

3.552

3.850

21

.686

.859

1.063

1.323

1.721

2.080

2.189

2.518

2.831

3.135

3.527

3.819

22

.686

.858

1.061

1.321

1.717

2.074

2.183

2.508

2.819

3.119

3.505

3.792

23

.685

.858

1.060

1.319

1.714

2.069

2.177

2.500

2.807

3.104

3.485

3.768

24

.685

.857

1.059

1.318

1.711

2.064

2.172

2.492

2.797

3.091

3.467

3.745

25

.684

.856

1.058

1.316

1.708

2.060

2.167

2.485

2.787

3.078

3.450

3.725

26

.684

.856

1.058

1.315

1.706

2.056

2.162

2.479

2.779

3.067

3.435

3.707

27

.684

.855

1.057

1.314

1.703

2.052

2.158

2.473

2.771

3.057

3.421

3.690

28

.683

.855

1.056

1.313

1.701

2.048

2.154

2.467

2.763

3.047

3.408

3.674

29

.683

.854

1.055

1.311

1.699

2.045

2.150

2.462

2.756

3.038

3.396

3.659

30

.683

.854

1.055

1.310

1.697

2.042

2.147

2.457

2.750

3.030

3.385

3.646

40

.681

.851

1.050

1.303

1.684

2.021

2.123

2.423

2.704

2.971

3.307

3.551

50

.679

.849

1.047

1.299

1.676

2.009

2.109

2.403

2.678

2.937

3.261

3.496

60

.679

.848

1.045

1.296

1.671

2.000

2.099

2.390

2.660

2.915

3.232

3.460

80

.678

.846

1.043

1.292

1.664

1.990

2.088

2.374

2.639

2.887

3.195

3.416

100

.677

.845

1.042

1.290

1.660

1.984

2.081

2.364

2.626

2.871

3.174

3.390

1000

.675

.842

1.037

1.282

1.646

1.962

2.056

2.330

2.581

2.813

3.098

3.300

\infty

.674

.841

1.036

1.282

1.645

1.960

2.054

2.326

2.576

2.807

3.091

3.291

Confidence level C

50%

60%

70%

80%

90%

95%

96%

98%

99%

99.5%

99.8%

99.9%

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Dan Finlay

Author: Dan Finlay

Expertise: Maths Subject Lead

Dan graduated from the University of Oxford with a First class degree in mathematics. As well as teaching maths for over 8 years, Dan has marked a range of exams for Edexcel, tutored students and taught A Level Accounting. Dan has a keen interest in statistics and probability and their real-life applications.

Roger B

Reviewer: Roger B

Expertise: Maths Content Creator

Roger's teaching experience stretches all the way back to 1992, and in that time he has taught students at all levels between Year 7 and university undergraduate. Having conducted and published postgraduate research into the mathematical theory behind quantum computing, he is more than confident in dealing with mathematics at any level the exam boards might throw at you.