Washer Sizes (Metric)

Metric Flat Washers

All sizes are in millimeters

		Form A		Form B		Form C
Nominal Size	Internal Diameter	Outer	Thickness	Outer	Thickness	Outer	Thickness
M1	1.1	2.5	0.3
M1.2	1.3	3	0.3
M1.4	1.5	3	0.3
M1.6	1.7	4	0.3
M2	2.2	5	0.3
M2.5	2.7	6.5	0.5
M3	3.2	7	0.5
M3.5	3.7	7	0.5
M4	4.3	9	0.8			10	0.8
M5	5.3	10	1	10	0.8	12.5	1
M6	6.4	12.5	1.6	12.5	0.8	14	1.6
M7	7.4	14	1.6	14	0.8
M8	8.4	17	1.6	17	1	21	1.6
M10	10.5	21	2	21	1.2	24	2
M12	13	24	2.5	24	1.6	28	2.5
M14	15	28	2.5	28	1.6	30	2.5
M16	17	30	3	30	2	34	3
M18	19	34	3	34	2	37	3
M20	21	37	3	37	2	39	3
	23	39	3	39	2	44	3
M24	25	44	4	44	2.5	50	4
M27	28	55	4	50	2.5	56	4
M30	31	56	4	56	2.5	60	4

Metric Spring Washers

All sizes are in millimeters

		Rectangular		Square
Nominal Size	Internal Diameter	Outer	Thickness	Outer	Thickness
M2	2.1	4.4	0.5
M2.5	2.6	5.1	0.6
M3	3.1	6.2	0.8	5.5	1
M3.5	3.6	6.7	0.8	6	1
M4	4.1	7.6	0.9	6.95	1.2
M5	5.1	9.2	1.2	8.55	1.5
M6	6.1	11.8	1.6	9.6	1.5
M8	8.1	14.8	2	12.75	2
M10	10.2	18.1	2.2	15.9	2.5
M12	12.2	21.1	2.5	17.9	2.5
M14	14.2	24.1	3	21.1	3
M16	16.2	27.4	3.5	24.3	3.5
M18	18.2	29.4	3.5	26.4	3.5
M20	20.2	33.6	4	30.5	4.5
M22	22.5	35.9	4	32.7	4.5
M24	24.5	40	5	35.7	5
M27	27.5	43	5	38.9	5
M30	30.5	48.2	6	43.9	6