ISO 888 Thread lengths for ISO metric fasteners (bolts)

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 length 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.

l <= 125303846505460667278
125 < l
l <= 200
l > 2005765697379859197
Dimensions in millimetres

Whilst the information is provided in good faith, Andrews Fasteners Ltd are not under any responsibility or liability in respect of errors or information that was found to be incorrect or for any reliance the user may place on it.

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