Metric

(DIN 127B / ISO 12944)

Size ID (mm) OD (mm) Height (mm)
M3 3.1 6.2 1.6
M4 4.1 7.6 1.8
M5 5.1 9.2 2.4
M6 6.1 11.8 3.2
M8 8.1 14.8 4.0
M10 10.2 18.1 4.4
M12 12.2 21.1 5.0

Imperial

ASME B18.21.1 - Helical Spring Lock Washers (Regular)

Size ID (in) OD (in) Thickness (in)
#4 0.114 0.209 0.025
#6 0.141 0.250 0.031
#8 0.167 0.293 0.040
#10 0.193 0.334 0.047
1/4" 0.252 0.487 0.062
5/16" 0.314 0.583 0.078
3/8" 0.377 0.680 0.094
1/2" 0.502 0.869 0.125