Hexagon Head Bolts: Dimensions and Specifications

This document provides detailed dimensional specifications for hexagon head bolts across a wide range of metric thread sizes, from M1.6 to M160. The data presented is crucial for engineers, manufacturers, and procurement specialists to ensure correct selection and application of these fasteners.

General Information

The diagrams illustrate key dimensions of hexagon head bolts, including:

d: Nominal thread diameter
L: Length of the bolt
b: Length of thread
k: Height of the hexagon head
s: Width across flats of the hexagon head
e: Width across corners of the hexagon head
ds: Diameter of the shank
dw: Diameter of the bearing face
c: Underside of head to start of thread
r: Radius at the underside of the head
k1: Height of the hexagon head minus chamfer
da: Diameter of the bearing face
P: Thread Pitch

Note on Point: The point shall be chamfered, or for threads ≤ M4, it may be as-rolled (sheared end).

Dimensional Tables

The following tables detail the specified dimensions for various thread sizes. Dimensions are provided in millimeters (mm) unless otherwise stated. Grade A and Grade B specifications are included where applicable, particularly for shank diameter (ds) and head height (k).

Table 1: Dimensions for M1.6 to M12 Bolts

Dimensions for M1.6 to M12 Bolts (mm)
Parameter	Thread Size (d)	M1.6	M2	M2.5	M3	(M3.5)	M4	M5	M6	(M7)	M8	M10	M12
P (Thread Pitch)		0.35	0.4	0.45	0.5	0.6	0.7	0.8	1	1	1.25	1.5	1.75
b (Length)	L≤125	9	10	11	12	13	14	16	18	20	22	26	30
	125	-	-	-	-	-	-	22	24	26	28	32	36
	L>200	-	-	-	-	-	-	-	-	-	-	-	45	49
c	min	0.1	0.1	0.1	0.15	0.15	0.15	0.15	0.15	0.15	0.15	0.15	0.15
c	max	0.25	0.25	0.25	0.4	0.4	0.4	0.5	0.5	0.5	0.6	0.6	0.6
da (max)		2	2.6	3.1	3.6	4.1	4.7	5.7	6.8	7.8	9.2	11.2	13.7
ds (max-nominal size)		1.6	2	2.5	3	3.5	4	5	6	7	8	10	12
ds (max-nominal size)	Grade A	1.46	1.86	2.36	2.86	3.32	3.82	4.82	5.82	6.78	7.78	9.78	11.73
dw (min)	Grade A	2.4	3.2	4.1	4.6	5.1	5.9	6.9	8.9	9.8	11.6	15.6	17.4
dw (min)	Grade B	-	-	-	-	-	-	-	-	-	-	-	-
e (min)	Grade A	3.41	4.32	5.45	6.01	6.58	7.66	8.79	11.05	12.12	14.38	18.9	21.1
e (min)	Grade B	-	-	-	-	-	-	-	-	-	-	-	-
k (Nominal Size)		1.1	1.4	1.7	2	2.4	2.8	3.5	4	4.8	5.3	6.4	7.5
k (Nominal Size)	min	0.98	1.28	1.58	1.88	2.28	2.68	3.35	3.85	4.65	5.15	6.22	7.32
k1 (min)		0.7	0.9	1.1	1.3	1.6	1.9	2.28	2.63	3.19	3.54	4.28	5.05
k1 (min)	min	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.25	0.25	0.4	0.4	0.6
s (max-nominal size)		3.2	4	5	5.5	6	7	8	10	11	13	17	19
s (max-nominal size)	Grade A	3.02	3.82	4.82	5.32	5.82	6.78	7.78	9.78	10.73	12.73	16.73	18.67

Table 2: Dimensions for M14 to M39 Bolts

Dimensions for M14 to M39 Bolts (mm)
Parameter	Thread Size (d)	(M14)	M16	(M18)	M20	(M22)	M24	(M27)	M30	(M33)	M36	(M39)
P (Thread Pitch)		2	2	2.5	2.5	2.5	3	3	3.5	3.5	4	4
b (Length)	L≤125	34	38	42	46	50	54	60	66	72	78	84
	125	40	44	48	52	56	60	66	72	78	84	90
	L>200	53	57	61	65	69	73	79	85	91	97	103
c	min	0.15	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.3
c	max	0.6	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	1
da (max)		15.7	17.7	20.2	22.4	24.4	26.4	30.4	33.4	36.4	39.4	42.4
ds (max-nominal size)		14	16	18	20	22	24	27	30	33	36	39
ds (max-nominal size)	Grade A	13.73	15.73	17.73	19.67	21.67	23.67	-	29.48	32.38	35.38	38.38
dw (min)	Grade A	20.5	22.5	25.3	28.2	30	33.6	-	38	42.7	46.6	51.1	55.9
dw (min)	Grade B	22	24.8	27.7	29.5	33.2	38	42.7	46.6	51.1	55.9	-
e (min)	Grade A	24.49	26.75	30.14	33.53	35.72	39.98	-	45.2	50.85	55.37	60.79	66.44
e (min)	Grade B	26.17	29.56	32.95	35.03	39.55	45.2	50.85	55.37	60.79	66.44	-
k (Nominal Size)		8.8	10	11.5	12.5	14	15	17	18.7	21	22.5	25
k (Nominal Size)	min	8.62	9.82	11.28	12.28	13.78	14.78	-	17	18.7	21	22.5	25
k1 (min)		5.96	6.8	7.8	8.5	9.6	10.3	11.7	12.8	14.4	15.5	17.2
k1 (min)	min	0.6	0.6	0.6	0.8	0.8	0.8	1	1	1	1	1
s (max-nominal size)		22	24	27	30	32	36	41	46	50	55	60
s (max-nominal size)	Grade A	21.67	23.67	26.67	29.67	31.61	35.38	-	40	45	49	53.8	58.8

Table 3: Dimensions for M42 to M72 Bolts

Dimensions for M42 to M72 Bolts (mm)
Parameter	Thread Size (d)	M42	(M45)	M48	(M52)	M56	(M60)	M64	(M68)	M72
P (Pitch)		4.5	4.5	5	5	5.5	5.5	6	6	6
b (Length)	L≤125	90	96	102	-	-	-	-	-	-
	125	96	102	108	116	124	132	140	148	156
	L>200	109	115	121	129	137	145	153	161	169
c	min	0.3	0.3	0.3	0.3	0.3	0.3	0.3	0.3	0.3
c	max	1	1	1	1	1	1	1	1	1
da (max)		45.6	48.6	52.6	56.6	63	67	71	75	79
ds (max-nominal size)		42	45	48	52	56	60	64	68	72
ds (max-nominal size)	Grade A	41.61	44.38	47.38	51.26	55.26	59.26	63.26	67.26	71.26
dw (min)		60.6	64.7	69.4	74.2	78.7	83.4	88.2	92.9	97.7
e (min)	Grade A	71.3	76.95	82.6	88.25	93.56	99.21	104.86	110.51	116.16
e (min)	Grade B	-	-	-	-	-	-	-	-	-
k (Nominal Size)		26	28	30	33	35	38	40	43	45
k (Nominal Size)	min	26.42	28.42	30.42	33.5	35.5	38.5	40.5	43.5	45.5
k1 (min)		17.9	19.3	20.9	22.8	24.2	26.2	27.6	29.8	31.2
k1 (min)	min	1.2	1.2	1.6	1.6	2	2	2	2	2
s (max-nominal size)		65	70	75	80	85	90	95	100	105
s (max-nominal size)	Grade A	63.1	68.1	73.1	78.1	82.8	87.8	92.8	97.8	102.8

Table 4: Dimensions for M76 to M160 Bolts

Dimensions for M76 to M160 Bolts (mm)
Parameter	Thread Size (d)	(M76)	M80	M90	M100	M110	M125	M140	M160
P (Pitch)		6	6	6	6	6	6	6	6
b (Length)	L≤125	-	-	-	-	-	-	-	-
	125	164	172	192	-	-	-	-	-
	L>200	177	185	205	225	245	275	305	345
c	min	-	-	-	-	-	-	-	-
c	max	1	2	2	2	2	2	2	2
da (max)		83	87	97	107	117	132	147	167
ds (max-nominal size)		76	88	90	100	110	125	140	160
ds (max-nominal size)	Grade A	75.26	79.26	89.13	99.13	109.13	124	139	159
dw (min)		102.1	106.9	121.1	135.4	144.9	168.6	185.6	214.1
e (min)	Grade A	121.81	127.46	144.08	161.02	172.32	200.57	220.8	254.7
e (min)	Grade B	-	-	-	-	-	-	-	-
k (Nominal Size)		48	50	57	63	69	79	88	100
k (Nominal Size)	min	48.5	50.5	57.6	63.6	69.6	79.6	88.7	100.7
k1 (min)		33.2	34.6	40.3	43.7	47.9	54.9	61.1	69.5
k1 (min)	min	2	2	2.5	2.5	2.5	2.5	2.5	2.5
s (max-nominal size)		110	115	130	145	155	180	200	230
s (max-nominal size)	Grade A	107.8	112.8	127.5	142.5	152.5	177.5	195.4	225.4

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