ISO Metric Special

Thread Form

ISO Metric Thread Form
  • p = Pitch
  • hn = Height of internal thread = 0.54127p
  • hs = Height of external thread = 0.61344p
  • r = Basic Radius = 0.1443p

Thread Tables

Nominal Diameter Pitch Basic Major Diameter Basic Effective Diameter Basic Minor Diameter of External Threads Basic Minor Diameter of Internal Threads Tapping Drill Clearance Drill
(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm)
1.7 0.35 1.7 1.473 1.27 1.321 1.35 1.8
2 0.45 2 1.708 1.448 1.513 1.55 2.1
2.3 0.4 2.3 2.04 1.809 1.867 1.9 2.4
2.6 0.45 2.6 2.308 2.048 2.113 2.15 2.7
3 0.6 3 2.61 2.264 2.35 2.4 3.1
4 0.75 4 3.513 3.08 3.188 3.2 4.1
5 0.9 5 4.415 3.896 4.026 4.1 5.1
5.5 0.9 5.5 4.915 4.396 4.526 4.6 5.6
8 0.75 8 7.513 7080 7.188 7.2 8.2
9 1 9 8.35 7.773 7.917 8 9.2
10 0.75 10 9.513 9.08 9.188 9.2 10.2
10 1 10 9.35 8.773 8.917 9 10.2
12 1 12 11.35 10.773 10.917 11 12.2
12 1.5 12 11.026 10.16 10.376 10.5 12.2
14 1.25 14 13.188 12.466 12.647 12.8 14.25
16 1 16 15.35 14.773 14.917 15 16.25
20 1 20 19.35 18.773 18.917 19 20.25
20 2 20 10.701 17.546 17.835 18 20.25
24 1 24 23.35 22.773 22.917 23 24.25
24 1.5 24 23.026 22.16 22.376 22.5 24.25
25 1.5 25 24.026 23.16 23.376 23.5 25.25
32 1.5 32 31.026 30.16 30.376 30.5 32.6