Metric Standard Thread Length for Bolts

Bolt Diameter Standard Thead Length (mm) *
Bolts 125mm and shorter Bolts longer than 125mm
3 12 -
4 14 -
5 16 22
6 18 24
7 20 26
8 22 28
10 26 32
12 30 36
14 34 40
16 38 44
18 42 48
20 46 52
* Important note: Some bolts may vary from the standard thread length.