Meanings of screws’specification

        We generally use “M number * number” to indicate the specification of the screw, so what do “M” and the numbers mean? Below let’s explain the meanings of some parameters about screw specifications.

  • “M”means the ordinary screws
  • The number after “M” indicates that the major diameter of the screw thread is **mm. For example M4x10, M4 means that the diameter of the screw thread is 4mm.
  • *number, here the number means the length of the screw thread (excluding the head thickness).
  • “p” means the pitch, that is the distance between two adjacent screw thread. Generally, it refers to the axial distance between the corresponding two points on the pitch line of two adjacent teeth on the thread in the thread pitch.


  • “s” means the size of two opposite parallel faces of the six sides of the screw. For example, M4-P0.7 nuts can only be connected with M4-P0.7 series bolts.
  • “k” means the thickness of the screw head.
  • “dk” means the diameter of the screw head.

        As shown in the picture:

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