Dimensions of ASME B18.3.1M Metric Socket Head Cap Screws

Dimensions of ASME B18.3.1M Metric Socket Head Cap Screws

Nominal Size and Thread PitchBody Diameter, DHead Diameter, AHead Height, HChamfer or Radius, S, MaxHexagon Socket Size, J, Nom.Spline Socket Size, M, Nom.Key Engagement, T, MinTransition Diameter, Ba, Max
MaxMinMaxMinMaxMin
M1.6 x 0.351.601.463.002.871.601.520.161.51.8290.802.0
M2 0.42.001.863.803.652.001.910.201.51.8291.002.6
M2.5 x 0.452.502.364.504.332.502.400.252.02.4381.253.1
M3 x 0.53.002.865.505.323.002.890.302.52.8191.503.6
M4 x 0.74.003.827.006.804.003.880.403.03.3782.004.7
M5 x 0.85.004.828.508.275.004.860.504.04.6482.505.7
M6 x 16.005.8210.009.746.005.850.605.05.4863.006.8
M8 x 1.258.007.7813.0012.708.007.830.806.07.3914.009.2
M10 x 1.510.009.7816.0015.6710.009.811.008.05.0011.2
M12 x 1.7512.0011.7318.0017.6312.0011.791.2010.06.0014.2
M14 x 2b14.0013.7321.0020.6014.0013.771.4012.07.0016.2
M16 x 216.0015.7324.0023.5816.0015.761.6014.08.0018.2
M20 x 2.520.0019.6730.0029.5320.0019.732.0017.010.0022.4
M24 x 324.0023.6736.0035.4824.0023.702.4019.012.0026.4
M30 x 3.530.0029.6745.0044.4230.0029.673.0022.015.0033.4
M36 x 436.0035.6154.0043.3736.0035.643.6027.018.0039.4
M42 x 4.542.0041.6163.0062.3142.0041.614.2032.021.0045.6
M48 x 548.0047.6172.0071.2748.0047.584.8036.024.0052.6
  • bThe M14X2 size is not recommended for use in new designs.
  • All dimensions are in millimeters
  • LG is a grip length and LB is body length.
  • For additional manufacturing and acceptance specificatons, see ASME B18.3.1M-1986.