No.

Diameter (approximate) in Inches.

Pitch in Inches.

Diameter in Millimetres.

Pitch in

Millimetres.

Threads per Inch.

25

•01

.0023

•25

•072

353

24

•011

•0031

•29

•08

317

23

•013

•0035

•33

•089

285

22

•015

•0039

•37

.098

259

21

•017

•0043

•32

•11

231

20

•019

•0047

.48

•12

212

19

•021

•0055

•54

•14

181

18

•024

.0059

•62

•15

169

17

.027

.0067

.7

•17

149

16

•031

•0075

•79

T9

131

15

.035

•0083

•9

•21

121

14

•039

•0031

1

•23

110

13

•044

•0038

1.2

.25

101

12

•051

.011

1.3

•28

907

11

•059

•0122

1.5

•31

8P9

10

•067

•0138

1.7

•35

72.6

9

•075

•0154

1.9

•39

651

8

•086

•0169

2.2

•43

59T

7

•038

•0189

2.5

•48

529

• 6

•11

•0209

2.8

•53

47.9

5

•126

•0232

3.2

•59

43

4

•142

•026

3.6

•66

38.5

3

•161

.0287

4.1

•73

34.8

2

185

•0319

47

•81

3P4

1

•209

•0354

53

•9

28.2

0

•236

•0394

6

1

25.4