Screw Thread d				M4	M5	M6	(M7)	M8	M10	M12	(M14)	M16	(M18)	M20	(M22)	M24	(M27)	M30	(M33)	M36	(M39)	M42	(M45)	M48	(M52)
P		Pitch		0.7	0.8	1	1	1.25	1.5	1.75	2	2	2.5	2.5	2.5	3	3	3.5	3.5	4	4	4.5	4.5	5	5
a		max		2.1	2.4	3	3	3.75	4.5	5.25	6	6	7.5	7.5	7.5	9	9	10.5	10.5	12	12	13.5	13.5	15	15
c		min		0.15	0.15	0.15	0.15	0.15	0.15	0.15	0.15	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.3	0.3	0.3	0.3	0.3
		max		0.4	0.5	0.5	0.5	0.6	0.6	0.6	0.6	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	1	1	1	1	1
da		max		4.7	5.7	6.8	7.8	9.2	11.2	13.7	15.7	17.7	20.2	22.4	24.4	26.4	30.4	33.4	36.4	39.4	42.4	45.6	48.6	52.6	56.6
dw		Grade A	min	5.9	6.9	8.9	9.6	11.6	15.6	17.4	20.5	22.5	25.3	28.2	30	33.6	-	-	-	-	-	-	-	-	-
		Grade B	min	5.7	6.7	8.7	9.4	11.4	15.4	17.2	20.1	22	24.8	27.7	29.5	33.2	38	42.7	46.5	51.1	55.9	59.9	64.7	69.4	74.2
e		Grade A	min	7.66	8.79	11.05	12.12	14.38	18.9	21.1	24.49	26.75	30.14	33.53	35.72	39.98	-	-	-	-	-	-	-	-	-
		Grade B	min	7.5	8.63	10.89	11.94	14.2	18.72	20.88	23.91	26.17	29.56	32.95	35.03	39.55	45.2	50.85	55.37	60.79	66.44	71.3	76.95	82.6	88.25
k		Nominal Size		2.8	3.5	4	4.8	5.3	6.4	7.5	8.8	10	11.5	12.5	14	15	17	18.7	21	22.5	25	26	28	30	33
		Grade A	min	2.68	3.35	3.85	4.65	5.15	6.22	7.32	8.62	9.82	11.28	12.28	13.78	14.78	-	-	-	-	-	-	-	-	-
			max	2.92	3.65	4.15	4.95	5.45	6.56	7.68	8.98	10.18	11.72	12.72	14.22	15.22	-	-	-	-	-	-	-	-	-
		Grade B	min	2.6	3.26	3.76	4.56	5.06	6.11	7.21	8.51	9.71	11.15	12.15	13.65	14.65	16.65	18.28	20.58	22.08	24.58	25.58	27.58	29.58	32.5
			max	3	3.74	4.24	5.04	5.54	6.69	7.79	9.09	10.29	11.85	12.85	14.35	15.35	17.35	19.12	21.42	22.92	25.42	26.42	28.42	30.42	33.5
k1		min		1.9	2.28	2.63	3.19	3.54	4.28	5.05	5.96	6.8	7.8	8.5	9.6	10.3	11.7	12.8	14.4	15.5	17.2	17.9	19.3	20.9	22.8
r		min		0.2	0.2	0.25	0.25	0.4	0.4	0.6	0.6	0.6	0.6	0.8	0.8	0.8	1	1	1	1	1	1.2	1.2	1.6	1.6
s		max=nominal size		7	8	10	11	13	17	19	22	24	27	30	32	36	41	46	50	55	60	65	70	75	80
		Grade A	min	6.78	7.78	9.78	10.73	12.73	16.73	18.67	21.67	23.67	26.67	29.67	31.61	35.38	-	-	-	-	-	-	-	-	-
		Grade B	min	6.64	7.64	9.64	10.57	12.57	16.57	18.48	21.16	23.16	26.15	29.16	31	35	40	45	49	53.8	58.8	63.1	68.1	73.1	78.1

Related Knowlege : The bolt threading size after hot dip galvanized surface treatment process will become bigger than zinc plated , so HDG bolt thread must match the over size hex nut or the nut can not be threaded up. The hot dip galvanized surface can offer very strong anti-rust performance than electric zinc plated or black oxide surface.