ISO (International Standards Organisation)
Metric Coarse Threads

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Angle of Thread = 60o Degrees

Diameter
mm		 Pitch
mm		 Root Diameter
Internal Threads		 Root Diameter
External Threads		 Tapping Drill Size
1 0.25 0.729 0.693 Number drill 69
(0.75 mm)
1.1 0.25 0.829 0.793 Number drill 66

(0.85 mm)
1.2 0.25 0.929 0.893 Number drill 63
(0.95 mm)
1.4 0.3 1.075 1.032 Number drill 59
(1.1 mm)
1.6 0.35 1.221 1.17 1.25 mm
(0.0492 inch)
1.8 0.35 1.421 1.37 1.45 mm
(0.0571 inch)
2 0.4 1.567 1.509 Number drill 52
(1.6 mm)
2.2 0.45 1.713 1.648 1.75 mm
(0.0689 inch)
2.5 0.45 2.013 1.948 Number drill 46
(2.05 mm)
3 0.5 2.459 2.387 Number drill 40
(2.5 mm)
3.5 0.6 2.85 2.764 Number drill 33
(2.9 mm)
4 0.7 3.242 3.141 3.3 mm
(0.1299 inch)
4.5 0.75 3.688 3.58 Number drill 25
(3.8 mm)
5 0.8 4.134 4.019 Number drill 20
(4.2 mm)
6 1 4.917 4.773 Number drill 10
(5 mm)
7 1 5.917 5.773 Letter drill B
(6 mm)
8 1.25 6.647 6.466 6.8 mm
(0.2677 inch)
9 1.25 7.647 7.466 7.8 mm
(0.3071 inch)
10 1.5 8.376 8.16 8.5 mm
(0.3346 inch
11 1.5 9.376 9.16 Letter drill V
(9.5 mm)
12 1.75 10.106 9.853 10.2 mm
(0.4016 inch)
14 2 11.835 11.546 12 mm
(0.4724 inch)
16 2 13.835 13.546 14 mm
(0.5512 inch)
18 2.5 15.294 14.933 15.5 mm
(0.6102 inch)
20 2.5 17.294 16.933 17.5 mm
(0.6890 inch)
22 2.5 19.294 18.933 19.5 mm
(0.7677 inch)
24 3 20.752 20.319 21 mm
(0.8268 inch)
27 3 23.752 23.319 24 mm
(0.9449 inch

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