UN standard (Class 2A) - conversion table

 from Nominal size to Major diameter

Nominal size

Major dia.(Inch) 

Major dia.(mm)

0-80 UNF

0.0600

1.5240

1-64 UNC

0.0730

1.8542

1-72 UNF

0.0730

1.8542

2-56 UNC

0.0860

2.1844

2-64 UNF

0.0860

2.1844

3-48 UNC

0.0990

2.5146

3-56 UNF

0.0990

2.5146

4-40 UNC

0.1120

2.8448

4-48 UNF

0.1120

2.8448

5-40 UNC

0.1250

3.1750

5-44 UNF

0.1250

3.1750

6-32 UNC

0.1380

3.5052

6-40 UNF

0.1380

3.5052

8-32 UNC

0.1640

4.1656

8-36 UNF

0.1640

4.1656

10-24 UNC

0.1900

4.8260

10-28 UNS

0.1900

4.8260

10-32 UNF

0.1900

4.8260

10-36 UNS

0.1900

4.8260

10-40 UNS

0.1900

4.8260

10-48 UNS

0.1900

4.8260

10-56 UNS

0.1900

4.8260

12-24 UNC

0.2160

5.4864

12-28 UNF

0.2160

5.4864

12-32 UNEF

.2160 

5.4864

12-36 UNS

0.2160

5.4864

12-40 UNS

0.2160

5.4864

12-48 UNS

0.2160

5.4864

12-56 UNS

0.2160

5.4864

1/4"-20 UNC 

0.2500

6.3500

 

Thread data - American UN

Diameter- Pitch Combinations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Threads per Inch

Size no.or inches

External

Series with graded pitches

Serieswith uniform(constant) pitches

Primary1

Secondar

in

 

 

 

UNC

UNF

UNEF

4UN

6UN

8UN

12UN

16UN

20UN

28UN

32UN

0

 

0.06

 

80

 

 

 

 

 

 

 

 

 

 

 

0.073

64

72

 

 

 

 

 

 

 

 

 

2

 

0.086

56

64

 

 

 

 

 

 

 

 

 

 

3

0.099

48

56

 

 

 

 

 

 

 

 

 

4

 

0.112

40

48

 

 

 

 

 

 

 

 

 

5

 

0.125

40

44

 

 

 

 

 

 

 

 

 

6

 

0.138

32

40

 

 

 

 

 

 

 

 

 

8

 

0.164

32

36

 

 

 

 

 

 

 

 

 

10

 

0.19

24

32

 

 

 

 

 

 

 

 

 

 

12

0.216

24

28

32

 

 

 

 

 

 

 

 

1/4"

 

0.25

20

28

32

 

 

 

 

 

 

 

 

5/ 16"

 

0.3125

18

24

32

 

 

 

 

 

20

28

 

318"

 

0.375

16

24

32

 

 

 

 

 

20

28

 

7/ 16"

 

0.4375

14

20

28

 

 

 

 

16

 

 

32

1/2"

 

0.5

13

20

28

 

 

 

 

16

 

 

32

9/ 16"

 

0.5625

12

18

24

 

 

 

 

16

20

28

32

5/8"

 

0.63

11

18

24

 

 

 

12

16

20

28

32

 

11/16"

0.69

 

 

24

 

 

 

12

16

20

28

32

3/4"

 

0.75

10

16

20

 

 

 

12

 

 

28

32

 

13/16"

0.81

 

 

20

 

 

 

12

16

 

28

32

718"

 

0.88

9

14

20

 

 

 

12

16

 

28

32

 

15/16"

0.94

 

 

20

 

 

 

12

16

 

28

32

1"

 

1.00

8

12

20

 

 

 

 

16

 

28

32

 

1 1116"

1.06

 

 

18

 

 

8

12

16

20

28

 

1 1/8"

 

1.13

7

12

18

 

 

8

 

16

20

28

 

 

13/16.

1.19

 

 

18

 

 

8

12

16

20

28

 

1 1/4"

 

1.25

7

12

18

 

 

8

 

16

20

28

 

 

15/16"

1.31

 

 

18

 

 

8

12

16

20

28

 

1 3/8"

 

1.38

6

12

18

 

 

8

 

16

20

28

 

 

17116"

1.44

 

 

18

 

6

8

12

16

20

28

 

1 112"

 

1.50

6

12

18

 

 

8

 

16

20

28

 

 

19116"

1.56

 

 

18

 

6

8

12

16

20

 

 

1 5/8'

 

1.63

 

 

18

 

6

8

12

16

20

 

 

 

1 11/16'

1.69

 

 

18

 

6

8

12

16

20

 

 

1 314"

 

1.75

5

 

 

 

6

8

12

16

20

 

 

 

1 13116'

1.81

 

 

 

 

6

8

12

16

20

 

 

1 7/8"

 

1.88

 

 

 

 

6

8

12

16

20

 

 

 

1 15/16"

1.94

 

 

 

 

6

8

12

16

20

 

 

2"

 

2.00

4.5

 

 

 

6

8

12

16

20

 

 

 

2 118"

2.13

 

 

 

 

6

8

12

16

20

 

 

2 1/4"

 

2.25

4.5

 

 

 

6

8

12

16

20

 

 

 

2 318"

2.38

 

 

 

 

6

8

12

16

20

 

 

 

 

Diameter- Pitch Combinations (Continued)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Threads per Inch

Size no.or inches

External

Series with graded pitches

Serieswith uniform(constant) pitches

Primary1

Secondar

in

 

 

 

UNC

UNF

UNEF

4UN

6UN

8UN

12UN

16UN

20UN

28UN

32UN

2 112"

 

2.50

4

 

 

 

6

8

12

16

20

 

 

 

2 5/8"

2.63

 

 

 

[4]

6

8

12

16

20

 

 

2 3/4"

 

2.75

4

 

 

 

6

8

12

16

20

 

 

 

2 718"

2.88

 

 

 

[4]

6

8

12

16

20

 

 

3"

 

3.00

4

 

 

 

6

8

12

16

20

 

 

 

3 1/8"

3.13

 

 

 

[4]

6

8

12

16

 

 

 

3 1/4"

 

3.25

4

 

 

 

6

8

12

16

 

 

 

 

3 3/8"

3.38

 

 

 

[4]

6

8

12

16

 

 

 

3 112·

 

3.50

4

 

 

 

6

8

12

16

 

 

 

 

3 5/8"

3.63

 

 

 

[4]

6

8

12

16

 

 

 

3 3/4"

 

3.75

4

 

 

 

6

8

12

16

 

 

 

 

3 7/8"

3.88

 

 

 

[4]

6

8

12

16

 

 

 

4"

 

4.00

4

 

 

 

6

8

12

16

 

 

 

 

4 1/8'

4.13

 

 

 

[4]

6

[8]

12

16

 

 

 

4 1/4"

 

4.25

 

 

 

4

6

[8]

12

16

 

 

 

 

4 3/8"

4.38

 

 

 

[4]

6

[8]

12

16

 

 

 

4 1/2"

 

4.50

 

 

 

4

6

[8]

12

16

 

 

 

 

4 5/8"

4.63

 

 

 

[4]

6

[8]

12

16

 

 

 

4 3/4"

 

4.75

 

 

 

4

6

[8]

12

16

 

 

 

 

4 7/8"

4.88

 

 

 

[4]

6

[8]

12

16

 

 

 

5"

 

5.00

 

 

 

4

6

[8]

12

16

 

 

 

 

5 1/8"

5.13

 

 

 

[4]

6

[8]

12

16

 

 

 

5 114"

 

5.25

 

 

 

4

6

[8]

12

16

 

 

 

 

5 3/8"

5.38

 

 

 

[4]

6

[8]

12

16

 

 

 

5 112"

 

5.50

 

 

 

4

6

[8]

12

16

 

 

 

 

5 5/8"

5.63

 

 

 

[4]

6

[8]

12

16

 

 

 

5 3/4"

 

5.75

 

 

 

4

6

[8]

12

16

 

 

 

 

5 7/8"

5.88

 

 

 

[4]

6

[8]

12

16

 

 

 

6"

 

6.00

 

 

 

4

6

[8]

12

16

 

 

 

 


 

Thread data - American UN

Thread Dimensions  UNC (External)tolerance class 2A

Dimensions in inches

 

 

 

 

 

 

 

Nominal dia. and tpi

Allowance

Major diameter

Pitch diameter

Minor diameter

 

 

max.

min.

max.

min.

 

.086-56

0.0006

0.0854

0.0813

0.0738

0.0717

0.0635

.112-40

0.0008

0.1112

0.1061

0.095

0.0925

0.0805

.125-40

0.0008

0.1242

0.1191

0.108

0.1054

0.0935

.138-32

0.0008

0.1372

0.1312

0.1169

0.1141

0.0989

.164-32

0.0009

0.1631

0.1571

0.1428

0.1399

0.1248

.190-24

0.001

0.189

0.1818

0.1619

0.1586

0.1379

.250-20

0.0011

0.2489

0.2408

0.2164

0.2127

0.1876

.3125-18

0.0012

0.3113

0.3026

0.2752

0.2712

0.2431

.375-16

0.0013

0.3737

0.3643

0.3331

0.3287

0.297

.4375-14

0.0014

0.4361

0.4258

0.3897

0.385

0.3485

.500-13

0.0015

0.4985

0.4876

0.4485

0.4435

0.4041

.5625-12

0.0016

0.5609

0.5495

0.5068

0.5016

0.4587

.625-11

0.0016

0.6234

0.6113

0.5644

0.5589

0.5119

.750-10

0.0018

0.7482

0.7353

0.6832

0.6773

0.6255

.875-9

0.0019

0.8731

0.8592

0.8009

0.7946

0.7368

1.000-8

0.002

0.998

0.983

0.9168

0.91

0.8446

1.125-7

0.0022

1.1228

1.1064

1.03

1.0228

0.9475

1.250-7

0.0022

1.2478

1.2314

1.155

1.1476

1.0725

1.375-6

0.0024

1.3726

1.3544

1.2643

1.2563

1.1681

1.500-6

0.0024

1.4976

1.4794

1.3893

1.3812

1.2931

1.750-5

0.0027

1.7473

1.7268

1.6174

1.6085

1.5019

2.000-4.5

0.0029

1.9971

1.9751

1.8528

1.8433

1.7245

2.250-4.5

0.0029

2.2471

2.2251

2.1028

2.0931

1.9745

2.500-4

0.0031

2.4969

2.4731

2.3345

2.3241

2.1902

2.750-4

0.0032

2.7468

2.723

2.5844

2.5739

2.4401

3.000-4

0.0032

2.9968

2.973

2.8344

2.8237

2.6901

3.250-4

0.0033

3.2467

3.2229

3.0843

3.0734

2.94

3.500-4 

0.0033

3.4967

3.4729

3.3343

3.3233

3.19

3.750-4

0.0034

3.7466

3.7228

3.5842

3.573

3.4399

4.000-4 

0.0034

3.9966

3.9728

3.8342

3.8229

3.6899

 


 

Thread data - American UN

Thread Dimensions  UNC (External)tolerance class 2A

Dimensions in mm

 

 

 

 

 

 

 

Nominal dia. and tpi

Allowance

Major diameter

Pitch diameter

Minor diameter

 

 

max.

min.

max.

min.

 

.086-56

0.015

2.169

2.065

1.875

1.821

1.613

.112-40

0.020

2.824

2.695

2.413

2.350

2.045

.125-40

0.020

3.155

3.025

2.743

2.677

2.375

.138-32

0.020

3.485

3.332

2.969

2.898

2.512

.164-32

0.023

4.143

3.990

3.627

3.553

3.170

.190-24

0.025

4.801

4.618

4.112

4.028

3.503

.250-20

0.028

6.322

6.116

5.497

5.403

4.765

.3125-18

0.030

7.907

7.686

6.990

6.888

6.175

.375-16

0.033

9.492

9.253

8.461

8.349

7.544

.4375-14

0.036

11.077

10.815

9.898

9.779

8.852

.500-13

0.038

12.662

12.385

11.392

11.265

10.264

.5625-12

0.041

14.247

13.957

12.873

12.741

11.651

.625-11

0.041

15.834

15.527

14.336

14.196

13.002

.750-10

0.046

19.004

18.677

17.353

17.203

15.888

.875-9

0.048

22.177

21.824

20.343

20.183

18.715

1.000-8

0.051

25.349

24.968

23.287

23.114

21.453

1.125-7

0.056

28.519

28.103

26.162

25.979

24.067

1.250-7

0.056

31.694

31.278

29.337

29.149

27.242

1.375-6

0.061

34.864

34.402

32.113

31.910

29.670

1.500-6

0.061

38.039

37.577

35.288

35.082

32.845

1.750-5

0.069

44.381

43.861

41.082

40.856

38.148

2.000-4.5

0.074

50.726

50.168

47.061

46.820

43.802

2.250-4.5

0.074

57.076

56.518

53.411

53.165

50.152

2.500-4

0.079

63.421

62.817

59.296

59.032

55.631

2.750-4

0.081

69.769

69.164

65.644

65.377

61.979

3.000-4

0.081

76.119

75.514

71.994

71.722

68.329

3.250-4

0.084

82.466

81.862

78.341

78.064

74.676

3.500-4 

0.084

88.816

88.212

84.691

84.412

81.026

3.750-4

0.086

95.164

94.559

91.039

90.754

87.373

4.000-4 

0.086

101.514

100.909

97.389

97.102

93.723

 


 

Thread Dimensions UNC (Internal) tolerance class 2B

Dimensions in inches

 

 

 

 

 

 

 

Nominal dia. and tpi

Minor diameter

Pitch diameter

Major diameter

min.

max.

min.

max.

Tolerance

.086-56

0.0667

0.0737

0.0744

0.0772

0.0028

0.086

.112-40

0.0849

0.0939

0.0958

0.0991

0.0033

0.112

.125 40

0.0979

0.1062

0.1088

0.1121

0.0033

0.125

.138·32

0.104

0.114

0.1177

0.1214

0.0037

0.138

.164·32

0.13

0.139

0.1437

0.1475

0.0038

0.164

.190-24

0.145

0.156

0.1629

0.1672

0.0043

0.19

.250·20

0.196

0.207

0.2175

0.2224

0.0049

0.25

.3125·18

0.252

0.265

0.2764

0.2817

0.0053

0.3125

.375-16

0.307

0.321

0.3344

0.3401

0.0057

0.375

..4375-14

0.36

0.376

0.3911

0.3972

0.0061

0.4375

.500-13

0.417

0.434

0.45

0.4565

0.0065

0.5

.5625·12

0.472

0.49

0.5084

0.5152

0.0068

0.5625

.625·11

0.527

0.546

0.566

0.5732

0.0072

0.625

.750-10

0.642

0.663

0.685

0.6927

0.0077

0.75

.875·9

0.755

0.778

0.8028

0.811

0.0082

0.875

1.000·8

0.865

0.89

0.9188

0.9276

0.0088

 

1.125·7

0.97

0.998

1.0322

1.0416

0.0094

1.125

1.250-7

1.095

1.123

1.1572

1.1668

0.0096

1.25

1.375-6

1.195

1.225

1.2667

1.2771

0.0104

1.375

1.500·6

1.32

1.35

1.3917

1.4022

0.0105

1.5

1.750-5

1.534

1.568

1.6201

1.6317

0.0116

1.75

2.000·4.5

1.759

1.795

1.8557

1.8681

0.0124

2

2.250-4.5

2.009

2.045

2.1057

2.1183

0.0126

2.25

2.500·4

2.229

2.267

2.3376

2.3511

0.0135

2.5

2.750-4

2.479

2.517

2.5876

2.6013

0.0137

2.75

3.000·4

2.729

2.767

2.8376

2.8515

0.0139

3

3.250·1

2.979

3.017

3.0876

3.1017

0.0141

3.25

3.500·4

3.229

3.267

3.3376

3.3519

0.0143

3.5

3.750·4

3.479

3.517

3.5876

3.6021

0.0145

3.75

4.000·4

3.729

3.767

3.8376

3.8523

0.0147

4

 


 

Thread Dimensions UNC (Internal) tolerance class 2B

Dimensions in mm

 

 

 

 

 

 

 

Nominal dia. and tpi

Minor diameter

Pitch diameter

Major diameter

min.

max.

min.

max.

Tolerance

.086-56

1.694

1.872

1.890

1.961

0.071

2.184

.112-40

2.156

2.385

2.433

2.517

0.084

2.845

.125 40

2.487

2.697

2.764

2.847

0.084

3.175

.138·32

2.642

2.896

2.990

3.084

0.094

3.505

.164·32

3.302

3.531

3.650

3.747

0.097

4.166

.190-24

3.683

3.962

4.138

4.247

0.109

4.826

.250·20

4.978

5.258

5.525

5.649

0.124

6.350

.3125·18

6.401

6.731

7.021

7.155

0.135

7.938

.375-16

7.798

8.153

8.494

8.639

0.145

9.525

..4375-14

9.144

9.550

9.934

10.089

0.155

11.113

.500-13

10.592

11.024

11.430

11.595

0.165

12.700

.5625·12

11.989

12.446

12.913

13.086

0.173

14.288

.625·11

13.386

13.868

14.376

14.559

0.183

15.875

.750-10

16.307

16.840

17.399

17.595

0.196

19.050

.875·9

19.177

19.761

20.391

20.599

0.208

22.225

1.000·8

21.971

22.606

23.338

23.561

0.224

0.000

1.125·7

24.638

25.349

26.218

26.457

0.239

28.575

1.250-7

27.813

28.524

29.393

29.637

0.244

31.750

1.375-6

30.353

31.115

32.174

32.438

0.264

34.925

1.500·6

33.528

34.290

35.349

35.616

0.267

38.100

1.750-5

38.964

39.827

41.151

41.445

0.295

44.450

2.000·4.5

44.679

45.593

47.135

47.450

0.315

50.800

2.250-4.5

51.029

51.943

53.485

53.805

0.320

57.150

2.500·4

56.617

57.582

59.375

59.718

0.343

63.500

2.750-4

62.967

63.932

65.725

66.073

0.348

69.850

3.000·4

69.317

70.282

72.075

72.428

0.353

76.200

3.250·1

75.667

76.632

78.425

78.783

0.358

82.550

3.500·4

82.017

82.982

84.775

85.138

0.363

88.900

3.750·4

88.367

89.332

91.125

91.493

0.368

95.250

4.000·4

94.717

95.682

97.475

97.848

0.373

101.600