Metric

(ISO 7089 / DIN 125)

Size ID (mm) OD (mm) Thickness (mm)
M3 3.2 7.0 0.5
M4 4.3 9.0 0.8
M5 5.3 10.0 1.0
M6 6.4 12.0 1.6
M8 8.4 16.0 1.6
M10 10.5 20.0 2.0
M12 13.0 24.0 2.5
M16 17.0 30.0 3.0
M20 21.0 37.0 3.0

Imperial

ASME B18.21.1 - Type A Plain Washers (Narrow)

Size ID (in) OD (in) Thickness (in)
#4 0.125 0.312 0.032
#6 0.156 0.375 0.049
#8 0.188 0.438 0.049
#10 0.219 0.500 0.049
1/4" 0.281 0.625 0.065
5/16" 0.344 0.750 0.065
3/8" 0.406 0.875 0.065
1/2" 0.531 1.062 0.095