The standard pitch of m3.5 is 3.5 mm, the m in m3.5 screw hole is a common thread symbol, and 3.5 indicates that the thread outer diameter is 3.5 mm and the pitch is 0.5mm, so the diameter of m3.5 screw hole is 3.5 mm. So if we take M3.5' s standard pitch as an example, then M3.5' s standard pitch is equal to 3.5 mm.