British Standard Fine Thread Chart

Thread Angle 55 degrees

OD

Decimal

TPI

Pitch

Core Dia

Thread
Depth

Radius

Hex
A/Flats

Head
Depth

Washer
Face
Dia

Standard
Nut
Depth

Lock
Nut
Depth

Tapping
Size

MM

Letter
or
Number

3/16

0.1875

32

0.03125

0.1475

0.020

0.0037

0.338

0.1562

3.9

5/32

7/32

0.2188

28

0.0357

0.1731

0.0229

0.0049

0.1831

4.6

14

1/4

0.250

26

0.0385

0.2007

0.0246

0.0053

0.445

0.176

0.428

0.200

0.185

0.2087

5.3

4

9/32

0.2812

26

0.0385

0.232

0.0246

0.0053

0.238

6.0

B

5/16

0.3125

22

0.0454

0.2543

0.0291

0.0062

0.525

0.218

0.508

0.250

0.210

0.2656

6.7

17/64

3/8

0.375

20

0.050

0.3110

0.0320

0.0069

0.600

0.260

0.582

0.312

0.260

0.3228

8.2

P

7/16

0.4375

18

0.0555

.03663

0.0356

0.0076

0.710

0.302

0.690

0.375

0.275

0.375

9.7

3/8

1/2

0.500

16

0.0625

0.420

0.0400

0.0086

0.820

0.343

0.800

0.437

0.300

0.4375

11.0

7/16

9/16

0.5625

16

0.0625

0.4825

0.040

0.0086

0.920

0.375

0.900

0.500

0.333

0.500

12.6

1/2

5/8

0.625

14

0.0714

0.5335

0.0457

0.0096

1.010

0.417

0.985

0.562

0.375

0.5469

14.0

35/64

11/16

0.6875

14

0.0714

0.596

0.0457

0.0098

1.100

0.6094

15.5

39/64

3/4

0.750

12

0.0833

0.6433

0.0534

0.0114

1.200

0.500

1.175

0.687

0.458

0.6562

16.7

21/32

13/16

0.8125

12

0.0833

0.7058

0.0534

0.0114

0.7188

18.3

23/32

7/8

0.875

11

0.0909

0.7586

0.0582

0.0125

1.300

0.583

1.273

0.750

0.500

0.7812

19.7

25/32

1

1.000

10

0.100

0.8719

0.064

0.0137

1.480

0.666

1.453

0.875

0.583

0.8906

22.7

57/64

1 1/8

1.125

9

0.111

0.9827

0.0711

0.0153

1.670

0.750

1.620

1.000

0.666

1.000

25.4

1

1 1/4

1.250

9

0.111

1.1077

0.0711

0.0153

1.860

0.830

1.795

1.125

0.750

1.125

28.6

1 - 1/8

1 3/8

1.375

8

0.125

1.2149

0.080

0.0172

2.050

0.920

1.985

1.250

0.833

1.2344

31.5

1 - 15/64

1 1/2

1.500

8

0.125

1.3399

0.080

0.0172

2.220

1.000

2.155

1.375

0.916

1.3594

34.5

1 - 23/64

1 5/8

1.625

8

0.125

1.465

0.080

0.0172

2.410

1.486

37.8

1 - 15/32

1 3/4

1.750

7

0.1425

1.567

0.0915

0.0196

2.580

1.170

2.495

1.625

1.083

1.600

40.7

1 - 5/8

2

2.000

7

0.1425

1.817

0.0915

0.0196

2.760

1.330

2.675

1.750

1.166

1.835

46.6

1 - 27/32

2 1/4

2.250

6

0.1667

2.036

0.1067

0.0229

3.150

2.050

52.4

2 - 1/16

2 1/2

2.500

6

0.1667

2.286

0.1067

0.0229

3.550

2.330

59.0

2 - 5/16

2 3/4

2.750

6

0.1667

2.536

0.1067

0.0229

3.890

2.560

65.0

2 - 9/16

3

3.000

5

0.200

2.743

0.1281

0.0275

4.187

2.780

70.6

2 - 25/32

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