ISO Metric Fine

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)
3 0.35 3 2.773 2.57 2.621 2.65 3.1
4 0.5 4 3.675 3.387 3.459 3.5 4.1
5 0.5 5 4.675 4.387 4.459 4.5 5.1
6 0.75 6 5.513 5.08 5.188 5.2 6.1
7 0.75 7 6.513 6.08 6.188 6.2 7.2
8 1 8 7.35 6.773 8.917 7 8.2
10 1.25 10 9.188 8.466 8.647 8.8 10.2
12 1.25 12 11.188 10.466 10.647 10.8 12.2
14 1.5 14 13.026 12.16 12.376 12.5 14.25
16 1.5 16 15.026 14.16 14.376 14.5 16.25
18 1.5 18 17.026 16.16 16.376 16.5 18.25
20 1.5 20 19.026 18.16 18.376 18.5 20.25
22 1.5 22 21.026 20.16 20.376 20.5 22.25
24 2 24 22.701 21.546 21.835 22 24.25
27 2 27 25.701 24.506 24.835 25 27.25
30 2 30 28.701 27.546 27.885 28 30.5