ISO 888: Thread lengths for ISO metric fasteners (bolts) - Andrews Fasteners CE Approved Bolts, Nuts & Washers
Andrews Fasteners Limited
0113 246 9992
+44 (0) 113 246 9992
ISO 888: Thread lengths for ISO metric fasteners (bolts) image

ISO 888: Thread lengths for ISO metric fasteners (bolts)

Calculation of thread lengths

Typical, unless specified in a product standard, dimensions for thread lengths (b) is calculated as follow:

  • for l <= 125 mm: b = 2d + 6mm
  • for 125 mm < l <= 200 mm: b = 2d + 12mm
  • for l > 200mm: b = 2d + 25mm

Where l is lenght of the bolt and b is the threaded part of the bolt.

For bolt, where lengths l <= 0.5d the bolt should be fully threaded.

Typical thread lengths (b) for popular sizes of fasteners

Diameter M12 M16 M20 M22 M24 M27 M30 M33 M36
l <= 125 30 38 46 50 54 60 66 72 78
125 < l
l <= 200
36 44 52 56 60 66 72 78 84
l > 200 57 65 69 73 79 85 91 97
%d bloggers like this: