ASME B18.2.1 Heavy Hex Cap Screws

Scope

ASME B18.2.1 Hweavy Hex Cap Screws dimension standard covers the dimensional requirements for product types of bolts and screws recognized as American National Standard. Also included are appendices covering gaging procedures, grade markings for bolts and screws, formulas on which dimensional data are based, and a specification to assist in identifying a product as being a screw or a bolt. Where questions arise concerning acceptance of product, the dimensions in the tables shall govern over recalculation by formula. Heavy hex structural bolts, formerly covered in ASME B18.2.1, are now covered in ASME B18.2.6, The Tables measurements are also converted into millimeters to make the information clearer and easier to to understand.

ASME B18.2.1 Heavy Hex Cap Screws Dimensions (mm)

Nominal Size		Body Diameter, E		Width Across Flats, F			Width Across Corners, G		Head Height, H			Minimum Wrenching Height, J	Thread Length, L_T		Transition Thread Length, Y	Maximum Total Runout of Bearing Surface FIM
Nominal Size		Max.	Min.	Basic	Max.	Min.	Max.	Min.	Basic	Max.	Min.	Minimum Wrenching Height, J	>6"	<6"	Reference	Maximum Total Runout of Bearing Surface FIM
ASME B18.2.1 - 3⁄8	9.53	9.53	9.14	17.46	17.48	16.99	20.17	19.38	5.95	6.17	5.74	4.06	25.40	31.75	7.92	0.36
ASME B18.2.1 - 1⁄2	12.70	12.70	12.24	22.23	22.23	21.59	25.65	24.61	7.94	8.20	7.67	5.46	31.75	38.10	9.78	0.41
ASME B18.2.1 - 5⁄8	15.88	15.88	15.37	26.99	26.97	26.19	31.17	29.85	9.92	10.24	9.60	6.83	38.10	44.45	11.56	0.48
ASME B18.2.1 - 3⁄4	19.05	19.05	18.52	31.75	31.75	30.78	36.65	35.13	11.91	12.27	11.56	8.23	44.45	50.80	12.70	0.56
ASME B18.2.1 - 7⁄8	22.23	22.23	21.64	36.51	36.53	35.41	42.16	40.36	13.89	14.30	13.49	9.60	50.80	57.15	14.12	0.64
ASME B18.2.1 - 1	25.40	25.40	24.79	41.28	41.28	40.01	47.65	45.62	15.48	15.93	15.01	10.57	57.15	63.50	15.88	0.71
ASME B18.2.1 - 1 1⁄8	28.58	28.58	27.89	46.04	46.02	44.60	53.16	50.85	17.46	18.24	16.71	11.71	63.50	69.85	18.14	0.81
ASME B18.2.1 - 1 1⁄4	31.75	31.75	31.06	50.80	50.80	49.23	58.65	56.11	19.84	20.65	19.02	13.46	69.85	76.20	18.14	0.89
ASME B18.2.1 - 1 3⁄8	34.93	34.93	34.16	55.56	55.58	53.82	64.16	61.37	21.43	22.30	20.57	14.45	76.20	82.55	21.16	0.97
ASME B18.2.1 - 1 1⁄2	38.10	38.10	37.34	60.33	60.33	58.42	69.65	66.60	23.81	24.74	22.91	16.26	82.55	88.90	21.16	1.04
ASME B18.2.1 - 1 5⁄8	41.28	41.28	40.41	65.09	65.07	63.02	75.16	71.86	25.40	26.37	24.43	17.63	88.90	95.25	23.09	1.12
ASME B18.2.1 - 1 3⁄4	44.45	44.45	43.59	69.85	69.85	67.61	80.65	77.09	27.78	28.80	26.77	19.00	95.25	101.60	25.40	1.22
ASME B18.2.1 - 1 7⁄8	47.63	47.63	46.71	74.61	74.63	72.24	86.16	82.35	29.37	30.43	28.30	20.37	101.60	107.95	25.40	1.32
ASME B18.2.1 - 2	50.80	50.80	49.89	79.38	79.38	76.84	91.64	87.60	30.96	32.08	29.85	20.96	107.95	114.30	28.22	1.40
ASME B18.2.1 - 2 1⁄4	57.15	57.15	56.24	88.90	88.90	86.06	102.64	98.09	34.93	36.14	33.71	23.70	...	127.00	28.22	1.55
ASME B18.2.1 - 2 1⁄2	63.50	63.50	62.51	98.43	98.43	95.25	113.64	108.59	30.96	40.21	37.57	26.47	...	139.70	31.75	1.73
ASME B18.2.1 - 2 3⁄4	69.85	69.85	68.86	107.95	107.95	104.44	124.64	119.08	26.99	44.30	41.45	29.24	...	152.40	31.75	1.88
ASME B18.2.1 - 3	76.20	76.20	75.21	117.48	117.48	113.67	135.64	129.59	47.63	49.15	46.10	32.77	...	165.10	31.75	2.06
ASME B18.2.1 - 3 1⁄4	82.55	82.55	81.53	127.00	127.00	122.89	146.66	140.08	50.80	54.00	50.75	35.53	...	177.80	31.75	2.31
ASME B18.2.1 - 3 1⁄2	88.90	88.90	87.91	136.53	136.53	132.08	157.66	150.57	57.15	57.30	53.85	37.69	...	190.50	31.75	2.49
ASME B18.2.1 - 3 3⁄4	95.25	95.25	94.26	146.05	146.05	141.27	168.66	161.06	60.33	62.15	58.50	40.94	...	203.20	31.75	2.67
ASME B18.2.1 - 4	101.60	101.60	100.61	155.58	155.58	150.50	179.65	171.58	63.50	65.43	61.57	43.10	...	215.90	31.75	2.84
ASME B18.2.1 - 4 1⁄4	107.95	107.95	107.26	165.10	165.10	159.72	190.65	182.07	69.85	70.31	66.24	46.38	...	228.60	31.75	3.02
ASME B18.2.1 - 4 1⁄2	114.30	114.30	113.61	174.63	174.63	168.91	201.65	192.56	73.03	73.56	69.29	48.51	...	241.30	31.75	3.20
ASME B18.2.1 - 4 3⁄4	120.65	120.65	119.96	184.15	184.15	178.10	212.65	203.05	76.20	78.44	73.96	51.77	...	254.00	31.75	3.38
ASME B18.2.1 - 5	127.00	127.00	126.30	193.68	193.68	187.33	223.65	213.56	79.38	81.71	77.04	53.92	...	266.70	31.75	3.56
ASME B18.2.1 - 5 1⁄4	133.35	133.35	132.65	203.20	203.20	196.55	234.65	224.05	85.73	86.56	81.69	57.18	...	279.40	31.75	3.73
ASME B18.2.1 - 5 1⁄2	139.70	139.70	139.00	212.73	212.73	205.74	245.64	234.54	88.90	89.87	84.79	59.36	...	292.10	31.75	3.91
ASME B18.2.1 - 5 3⁄4	146.05	146.05	145.35	222.25	222.25	214.93	256.64	245.03	92.08	94.72	89.43	62.61	...	304.80	31.75	4.09
ASME B18.2.1 - 6	152.40	152.40	151.70	231.78	231.78	224.16	267.64	255.52	95.25	97.99	92.51	64.74	...	317.50	31.75	4.27
GENERAL NOTES: (a) Wrenching Height, J. Wrenching height is a distance measured from the bearing surface up the side of the head at the corners. The width across corners shall be within specified limits for the full wrenching height. (b) Refer to section 4 for further information.

ASME B18.2.1 Heavy Hex Cap Screws Length Tolerance (mm)

Nominal Length	Nominal Size (inches)
Nominal Length	1/4 to 3/8	7/16 and 1/2	9/16 to 3/4	7/8 and 1	1 1/8 to 1 1/2	Over 1 1/2
Up to 25.4 mm, incl.	+0.000 0.762	+0.000 0.762	+0.000 0.762	...	...	...
Over 25.4 mm to 63.5 mm, incl.	+0.000 1.016	+0.000 1.524	+0.000 2.032	+0.000 2.540	+0.000 3.048	+0.000 4.572
Over 63.5 mm to 101.6 mm, incl.	+0.000 1.524	+0.000 2.032	+0.000 2.540	+0.000 3.556	+0.000 4.064	+0.000 5.080
Over 101.6 mm to 152.4 mm, incl.	+0.000 2.540	+0.000 2.540	+0.000 2.540	+0.000 4.064	+0.000 4.572	+0.000 5.588
Longer than 152.4 mm	+0.000 4.572	+0.000 4.572	+0.000 4.572	+0.000 5.080	+0.000 5.588	+0.000 6.096

ASME B18.2.1 Heavy Hex Cap Screws Lengths (mm)

Nominal Size	Nominal Length, Lg, max. / Lb, min.
	1-1/4		1-3/8		1-1/2		1-5/8		1-3/4		1-7/8		2		2-1/8		2-1/4		2-3/8		2-1/2		2-5/8		2-3/4		2-7/8		3		3-1/4		3-1/2		3-3/4		4		4-1/4		4-1/2		4-3/4		5		5-1/4		5-1/2		5-3/4		6		6-1/4		6-1/2		6-3/4		7		7-1/4		7-1/2		7-3/4		8		8-1/4		8-1/2		8-3/4		9		9-1/4		9-1/2		9-3/4		10		11		12
	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.
1/4	0.50	0.25	0.63	0.38	0.75	0.50	0.88	0.62	1.00	0.75	1.12	0.88	1.25	1.00	1.38	1.12	1.50	1.25	1.62	1.38	1.75	1.50	1.88	1.62	2.00	1.75	2.12	1.88	2.52	2.00	2.50	2.25	2.75	2.50	3.00	2.75	3.25	3.00	3.50	3.25	3.75	3.50	4.00	3.75	4.25	4.00	4.50	4.25	4.75	4.50	5.00	4.75	5.25	5.00	5.25	5.00	5.50	5.25	5.75	5.50	6.00	5.75	6.25	6.00	6.50	6.25	6.75	6.50	7.00	6.75	7.25	7.00	7.50	7.25	7.75	7.50	8.00	7.75	8.25	8.00	8.50	8.25	8.75	8.50	9.00	8.75	10.00	9.75	11.00	10.75
5/16	Full thread		0.50	0.22	0.62	0.35	0.75	0.47	0.88	0.60	1.00	0.72	1.12	0.85	1.25	0.97	1.38	1.10	1.50	1.22	1.62	1.35	1.75	1.47	1.88	1.60	2.00	1.72	2.12	1.85	2.38	2.10	2.62	2.35	2.88	2.60	3.12	2.85	3.38	3.10	3.62	3.35	3.88	3.60	4.12	3.85	4.38	4.10	4.62	4.35	4.88	4.60	5.12	4.85	5.12	4.85	5.38	5.10	5.62	5.35	5.88	5.60	6.12	5.85	6.38	6.10	6.62	6.35	6.88	6.60	7.12	6.85	7.38	7.10	7.62	7.35	7.88	7.60	8.12	7.85	8.38	8.10	8.62	8.35	8.88	8.60	9.88	9.60	10.88	10.60
3/8	Full thread		Full thread		0.50	0.19	0.62	0.31	0.75	0.44	0.88	0.56	1.00	0.69	1.12	0.81	1.25	0.94	1.38	1.06	1.50	1.19	1.62	1.31	1.75	1.44	1.88	1.56	2.00	1.69	2.25	1.94	2.50	2.19	2.75	2.44	3.00	2.69	3.25	2.94	3.50	3.19	3.75	3.44	4.00	3.69	4.25	3.94	4.50	4.19	4.75	4.44	5.00	4.69	5.00	4.69	5.25	4.94	5.50	5.19	5.75	5.44	6.00	5.69	6.25	5.94	6.50	6.19	6.75	6.44	7.00	6.69	7.25	6.94	7.50	7.19	7.75	7.44	8.00	7.69	8.25	7.94	8.50	8.19	8.75	8.44	9.75	9.44	10.75	10.44
7/16	Full thread		Full thread		Full thread		Full thread		0.63	0.27	0.75	0.39	0.88	0.52	1.00	0.64	1.12	0.77	1.25	0.89	1.38	1.02	1.50	1.14	1.62	1.27	1.75	1.39	1.88	1.52	2.12	1.77	2.38	2.02	2.62	2.27	2.88	2.52	3.12	2.77	3.38	3.02	3.62	3.27	3.88	3.52	4.12	3.77	4.38	4.02	4.63	4.27	4.88	4.52	4.88	4.52	5.12	4.77	5.38	5.02	5.62	5.27	5.88	5.52	6.12	5.77	6.38	6.02	6.62	6.27	6.88	6.52	7.12	6.77	7.38	7.02	7.62	7.27	7.88	7.52	8.12	7.77	8.38	8.02	8.62	8.27	9.62	9.27	10.62	10.27
1/2	Full thread		Full thread		Full thread		Full thread		Full thread		0.63	0.24	0.75	0.38	0.88	0.49	1.00	0.62	1.12	0.74	1.25	0.86	1.38	0.99	1.50	1.12	1.62	1.24	1.75	1.36	2.00	1.62	2.25	1.86	2.50	2.12	2.75	2.36	3.00	2.62	3.25	2.86	3.50	3.12	3.75	3.36	4.00	3.62	4.25	3.87	4.50	4.12	4.75	4.36	4.75	4.36	5.00	4.62	5.25	4.86	5.50	5.12	5.75	5.36	6.00	5.62	6.25	5.87	6.50	6.12	6.75	6.36	7.00	6.62	7.25	6.86	7.50	7.12	7.75	7.36	8.00	7.62	8.25	7.86	8.50	8.12	9.50	9.12	10.50	10.12
9/16	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		0.75	0.33	0.88	0.45	1.00	0.58	1.12	0.75	1.25	0.83	1.38	0.96	1.50	1.08	1.62	1.21	1.88	1.46	2.12	1.71	2.38	1.96	2.62	2.21	2.88	2.46	3.12	2.71	3.38	2.96	3.62	3.21	3.88	3.46	4.12	3.71	4.38	3.96	4.62	4.21	4.62	4.21	4.88	4.46	5.12	4.71	5.38	4.96	5.62	5.20	5.88	5.46	6.12	5.71	6.38	5.96	6.62	6.21	6.88	6.46	7.12	6.71	7.38	6.96	7.62	7.21	7.88	7.46	8.12	7.71	8.38	7.96	9.38	8.96	10.38	9.96
5/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		0.75	0.30	0.88	0.42	1.00	0.55	1.12	0.67	1.25	0.80	1.38	0.92	1.50	1.05	1.75	1.30	2.00	1.55	2.25	1.80	2.50	2.05	2.75	2.30	3.00	2.55	3.25	2.80	3.50	3.05	3.75	3.30	4.00	3.55	4.25	3.80	4.50	4.05	4.50	4.05	4.75	4.30	5.00	4.55	5.25	4.80	5.50	5.05	5.75	5.30	6.00	5.55	6.25	5.80	6.50	6.05	6.75	6.30	7.00	6.55	7.25	6.80	7.50	7.05	7.75	7.30	8.00	7.55	8.25	7.80	9.25	8.80	10.25	9.80
3/4	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		1.12	0.67	1.25	0.80	1.38	0.92	1.50	1.05	1.50	1.00	1.75	1.25	2.00	1.50	2.25	1.75	2.50	2.00	2.75	2.25	3.00	2.50	3.25	2.75	3.50	3.00	3.75	3.25	4.00	3.50	4.25	3.75	4.25	3.75	4.50	4.00	4.75	4.25	5.00	4.50	5.25	4.75	5.50	5.00	5.75	5.25	6.00	5.50	6.25	5.75	6.50	6.00	6.75	6.25	7.00	6.50	7.25	6.75	7.50	7.00	7.75	7.25	8.00	7.50	9.00	8.50	10.00	9.50
7/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		1.00	0.50	1.12	0.62	1.25	0.75	1.25	0.69	1.50	0.94	1.75	1.19	2.00	1.44	2.25	1.69	2.50	1.94	2.75	2.19	3.00	2.44	3.25	2.69	3.50	2.94	3.75	3.19	4.00	3.44	4.00	3.44	4.25	3.69	4.50	3.94	4.75	4.19	5.00	4.44	5.25	4.69	5.50	4.94	5.75	5.19	6.00	5.44	6.25	5.69	6.50	5.94	6.75	6.19	7.00	6.44	7.25	6.89	7.50	6.94	7.75	7.19	8.75	8.19	9.75	9.19
1	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		0.88	0.32	1.00	0.44	1.00	0.38	1.25	0.62	1.50	0.88	1.75	1.12	2.00	1.38	2.25	1.62	2.50	1.88	2.75	2.12	3.00	2.38	3.25	2.62	3.50	2.88	3.75	3.12	3.75	3.12	4.00	3.38	4.25	3.63	4.50	3.88	4.75	4.12	5.00	4.38	5.25	4.52	5.50	4.88	5.75	5.12	6.00	5.38	6.25	5.62	6.50	5.88	6.75	6.12	7.00	6.38	7.25	6.62	7.50	6.88	8.50	7.88	9.50	8.88
1-1/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		1.25	0.54	1.50	0.79	1.75	1.04	2.00	1.29	2.25	1.54	2.50	1.79	2.75	2.04	3.00	2.29	3.25	2.54	3.50	2.79	3.50	2.79	3.75	3.04	4.00	3.29	4.25	3.54	4.50	3.79	4.75	4.04	5.00	4.29	5.25	4.54	5.50	4.79	5.75	5.04	6.00	5.29	6.25	5.54	6.50	5.79	6.75	6.04	7.00	6.29	7.25	6.54	8.25	7.54	9.25	8.54
1-1/4	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		1.25	0.54	1.50	0.79	1.75	1.04	2.00	1.29	2.25	1.54	2.50	1.79	2.75	2.04	3.00	2.29	3.25	2.54	3.25	2.54	3.50	2.79	3.75	3.04	4.00	3.29	4.25	3.54	4.50	3.79	4.75	4.04	5.00	4.29	5.25	4.54	5.50	4.79	5.75	5.04	6.00	5.29	6.25	5.54	6.50	5.79	6.75	6.04	7.00	6.29	8.00	7.29	9.00	8.29
1-3/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		1.50	0.79	1.75	1.04	2.00	1.29	2.25	1.54	2.50	1.79	2.75	2.04	3.00	2.29	3.25	2.54	3.25	2.54	3.50	2.79	3.75	3.04	4.00	3.29	4.25	3.54	4.50	3.79	4.75	4.04	5.00	4.29	5.25	4.54	5.50	4.79	5.75	5.04	6.00	5.29	6.25	5.54	6.50	5.79	6.75	6.04	7.75	7.04	8.75	8.04
1-1/2	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		1.50	0.67	1.75	0.92	2.00	1.17	2.25	1.42	2.50	1.67	2.75	1.92	2.75	1.92	3.00	2.17	3.25	2.42	3.50	2.67	3.75	2.92	4.00	3.17	4.25	3.42	4.50	3.67	4.75	3.92	5.00	4.17	5.25	4.42	5.50	4.67	5.75	4.92	6.00	5.17	6.25	5.42	6.50	5.67	7.50	6.67	8.50	7.67

ASME B18.2.1 Heavy Hex Cap Screws Dimensions (Inch)

Nominal Size		Body Diameter, E		Width Across Flats, F			Width Across Corners, G		Head Height, H			Minimum Wrenching Height, J	Thread Length, L_T		Transition Thread Length, Y	Maximum Total Runout of Bearing Surface FIM
Nominal Size		Max.	Min.	Basic	Max.	Min.	Max.	Min.	Basic	Max.	Min.	Minimum Wrenching Height, J	">6""	"<6""< /th>	Reference	Maximum Total Runout of Bearing Surface FIM
ASME B18.2.1 - 3⁄8	0.375	0.375	0.36	11⁄16	0.688	0.669	0.794	0.763	15⁄64	0.243	0.226	0.16	1	1.25	0.312	0.014
ASME B18.2.1 - 1⁄2	0.5	0.5	0.482	7⁄8	0.875	0.85	1.01	0.969	5⁄16	0.323	0.302	0.215	1.25	1.5	0.385	0.016
ASME B18.2.1 - 5⁄8	0.625	0.625	0.605	1 1⁄16	1.062	1.031	1.227	1.175	25⁄64	0.403	0.378	0.269	1.5	1.75	0.455	0.019
ASME B18.2.1 - 3⁄4	0.75	0.75	0.729	1 1⁄4	1.25	1.212	1.443	1.383	15⁄32	0.483	0.455	0.324	1.75	2	0.5	0.022
ASME B18.2.1 - 7⁄8	0.875	0.875	0.852	1 7⁄16	1.438	1.394	1.66	1.589	35⁄64	0.563	0.531	0.378	2	2.25	0.556	0.025
ASME B18.2.1 - 1	1	1	0.976	1 5⁄8	1.625	1.575	1.876	1.796	39⁄64	0.627	0.591	0.416	2.25	2.5	0.625	0.028
ASME B18.2.1 - 1 1⁄8	1.125	1.125	1.098	1 13⁄16	1.812	1.756	2.093	2.002	11⁄16	0.718	0.658	0.461	2.5	2.75	0.714	0.032
ASME B18.2.1 - 1 1⁄4	1.25	1.25	1.223	2	2	1.938	2.309	2.209	25⁄32	0.813	0.749	0.53	2.75	3	0.714	0.035
ASME B18.2.1 - 1 3⁄8	1.375	1.375	1.345	2 3⁄16	2.188	2.119	2.526	2.416	27⁄32	0.878	0.81	0.569	3	3.25	0.833	0.038
ASME B18.2.1 - 1 1⁄2	1.5	1.5	1.47	2 3⁄8	2.375	2.3	2.742	2.622	15⁄16	0.974	0.902	0.64	3.25	3.5	0.833	0.041
ASME B18.2.1 - 1 5⁄8	1.625	1.625	1.591	2 9⁄16	2.562	2.481	2.959	2.829	1	1.038	0.962	0.694	3.5	3.75	0.909	0.044
ASME B18.2.1 - 13⁄4	1.75	1.75	1.716	2 3⁄4	2.75	2.662	3.175	3.035	1 3⁄32	1.134	1.054	0.748	3.75	4	1	0.048
ASME B18.2.1 - 1 7⁄8	1.875	1.875	1.839	2 15⁄16	2.938	2.844	3.392	3.242	1 5⁄32	1.198	1.114	0.802	4	4.25	1	0.052
ASME B18.2.1 - 2	2	2	1.964	3 1⁄8	3.125	3.025	3.608	3.449	1 7⁄32	1.263	1.175	0.825	4.25	4.5	1.111	0.055
ASME B18.2.1 - 2 1⁄4	2.25	2.25	2.214	3 1⁄2	3.5	3.388	4.041	3.862	1 3⁄8	1.423	1.327	0.933	...	5	1.111	0.061
ASME B18.2.1 - 2 1⁄2	2.5	2.5	2.461	3 7⁄8	3.875	3.75	4.474	4.275	1 7⁄32	1.583	1.479	1.042	...	5.5	1.25	0.068
ASME B18.2.1 - 2 3⁄4	2.75	2.75	2.711	4 1⁄4	4.25	4.112	4.907	4.688	1 1⁄16	1.744	1.632	1.151	...	6	1.25	0.074
ASME B18.2.1 - 3	3	3	2.961	4 5⁄8	4.625	4.475	5.34	5.102	1 7⁄8	1.935	1.815	1.29	...	6.5	1.25	0.081
ASME B18.2.1 - 3 1⁄4	3.25	3.25	3.21	5	5	4.838	5.774	5.515	2	2.126	1.998	1.399	...	7	1.25	0.091
ASME B18.2.1 - 31⁄2	3.5	3.5	3.461	5 3⁄8	5.375	5.2	6.207	5.928	2 1⁄4	2.256	2.12	1.484	...	7.5	1.25	0.098
ASME B18.2.1 - 3 3⁄4	3.75	3.75	3.7109	5 3⁄4	5.75	5.562	6.64	6.341	2 3⁄8	2.447	2.303	1.612	...	8	1.25	0.105
ASME B18.2.1 - 4	4	4	3.9609	6 1⁄8	6.125	5.925	7.073	6.755	2 1⁄2	2.576	2.424	1.697	...	8.5	1.25	0.112
ASME B18.2.1 - 4 1⁄4	4.25	4.25	4.2228	6 1⁄2	6.5	6.288	7.506	7.168	2 3⁄4	2.768	2.608	1.826	...	9	1.25	0.119
ASME B18.2.1 - 4 1⁄2	4.5	4.5	4.4727	6 7⁄8	6.875	6.65	7.939	7.581	2 7⁄8	2.896	2.728	1.91	...	9.5	1.25	0.126
ASME B18.2.1 - 4 3⁄4	4.75	4.75	4.7227	7 1⁄4	7.25	7.012	8.372	7.994	3	3.088	2.912	2.038	...	10	1.25	0.133
ASME B18.2.1 - 5	5	5	4.9726	7 5⁄8	7.625	7.375	8.805	8.408	3 1⁄8	3.217	3.033	2.123	...	10.5	1.25	0.14
ASME B18.2.1 - 51⁄4	5.25	5.25	5.2226	8	8	7.738	9.238	8.821	3 3⁄8	3.408	3.216	2.251	...	11	1.25	0.147
ASME B18.2.1 - 51⁄2	5.5	5.5	5.4726	8 3⁄8	8.375	8.1	9.671	9.234	3 1⁄2	3.538	3.338	2.337	...	11.5	1.25	0.154
ASME B18.2.1 - 53⁄4	5.75	5.75	5.7225	8 3⁄4	8.75	8.462	10.104	9.647	3 5⁄8	3.729	3.521	2.465	...	12	1.25	0.161
ASME B18.2.1 - 6	6	6	5.9725	9 1⁄8	9.125	8.825	10.537	10.06	3 3⁄4	3.858	3.642	2.549	...	12.5	1.25	0.168
GENERAL NOTES: (a) Wrenching Height, J. Wrenching height is a distance measured from the bearing surface up the side of the head at the corners. The width across corners shall be within specified limits for the full wrenching height. (b) Refer to section 4 for further information.

ASME B18.2.1 Heavy Hex Cap Screws Length Tolerance (Inch)

Nominal Length	Nominal Size
Nominal Length	1/4 to 3/8	7/16 and 1/2	9/16 to 3/4	7/8 and 1	1 1/8 to 1 1/2	Over 1 1/2
Up to 1 in., incl.	+0.00 0.03	+0.00 0.03	+0.00 0.03	...	...	...
Over 1 in. to 2 1/2 in., incl.	+0.00 0.04	+0.00 0.06	+0.00 0.08	+0.00 0.10	+0.00 0.12	+0.00 0.18
Over 2 1/2 in. to 4 in., incl.	+0.00 0.06	+0.00 0.08	+0.00 0.10	+0.00 0.14	+0.00 0.16	+0.00 0.20
Over 4 in. to 6 in., incl.	+0.00 0.10	+0.00 0.10	+0.00 0.10	+0.00 0.16	+0.00 0.18	+0.00 0.22
Longer than 6 in.	+0.00 0.18	+0.00 0.18	+0.00 0.18	+0.00 0.20	+0.00 0.22	+0.00 0.24

ASME B18.2.1 Heavy Hex Cap Screws Lengths (Inch)

Nominal Size	Nominal Length, Lg, max. / Lb, min.
	1-1/4		1-3/8		1-1/2		1-5/8		1-3/4		1-7/8		2		2-1/8		2-1/4		2-3/8		2-1/2		2-5/8		2-3/4		2-7/8		3		3-1/4		3-1/2		3-3/4		4		4-1/4		4-1/2		4-3/4		5		5-1/4		5-1/2		5-3/4		6		6-1/4		6-1/2		6-3/4		7		7-1/4		7-1/2		7-3/4		8		8-1/4		8-1/2		8-3/4		9		9-1/4		9-1/2		9-3/4		10		11		12
	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.	L_g Max.	L_b Min.
1/4	12.70	6.35	16.00	9.65	19.05	12.70	22.35	15.75	25.40	19.05	28.45	22.35	31.75	25.40	35.05	28.45	38.10	31.75	41.15	35.05	44.45	38.10	47.75	41.15	50.80	44.45	53.85	47.75	64.01	50.80	63.50	57.15	69.85	63.50	76.20	69.85	82.55	76.20	88.90	82.55	95.25	88.90	101.60	95.25	107.95	101.60	114.30	107.95	120.65	114.30	127.00	120.65	133.35	127.00	133.35	127.00	139.70	133.35	146.05	139.70	152.40	146.05	158.75	152.40	165.10	158.75	171.45	165.10	177.80	171.45	184.15	177.80	190.50	184.15	196.85	190.50	203.20	196.85	209.55	203.20	215.90	209.55	222.25	215.90	228.60	222.25	254.00	247.65	279.40	273.05
5/16	Full thread		12.70	5.59	15.75	8.89	19.05	11.94	22.35	15.24	25.40	18.29	28.45	21.59	31.75	24.64	35.05	27.94	38.10	30.99	41.15	34.29	44.45	37.34	47.75	40.64	50.80	43.69	53.85	46.99	60.45	53.34	66.55	59.69	73.15	66.04	79.25	72.39	85.85	78.74	91.95	85.09	98.55	91.44	104.65	97.79	111.25	104.14	117.35	110.49	123.95	116.84	130.05	123.19	130.05	123.19	136.65	129.54	142.75	135.89	149.35	142.24	155.45	148.59	162.05	154.94	168.15	161.29	174.75	167.64	180.85	173.99	187.45	180.34	193.55	186.69	200.15	193.04	206.25	199.39	212.85	205.74	218.95	212.09	225.55	218.44	250.95	243.84	276.35	269.24
3/8	Full thread		Full thread		12.70	4.83	15.75	7.87	19.05	11.18	22.35	14.22	25.40	17.53	28.45	20.57	31.75	23.88	35.05	26.92	38.10	30.23	41.15	33.27	44.45	36.58	47.75	39.62	50.80	42.93	57.15	49.28	63.50	55.63	69.85	61.98	76.20	68.33	82.55	74.68	88.90	81.03	95.25	87.38	101.60	93.73	107.95	100.08	114.30	106.43	120.65	112.78	127.00	119.13	127.00	119.13	133.35	125.48	139.70	131.83	146.05	138.18	152.40	144.53	158.75	150.88	165.10	157.23	171.45	163.58	177.80	169.93	184.15	176.28	190.50	182.63	196.85	188.98	203.20	195.33	209.55	201.68	215.90	208.03	222.25	214.38	247.65	239.78	273.05	265.18
7/16	Full thread		Full thread		Full thread		Full thread		16.00	6.86	19.05	9.91	22.35	13.21	25.40	16.26	28.45	19.56	31.75	22.61	35.05	25.91	38.10	28.96	41.15	32.26	44.45	35.31	47.75	38.61	53.85	44.96	60.45	51.31	66.55	57.66	73.15	64.01	79.25	70.36	85.85	76.71	91.95	83.06	98.55	89.41	104.65	95.76	111.25	102.11	117.60	108.46	123.95	114.81	123.95	114.81	130.05	121.16	136.65	127.51	142.75	133.86	149.35	140.21	155.45	146.56	162.05	152.91	168.15	159.26	174.75	165.61	180.85	171.96	187.45	178.31	193.55	184.66	200.15	191.01	206.25	197.36	212.85	203.71	218.95	210.06	244.35	235.46	269.75	260.86
1/2	Full thread		Full thread		Full thread		Full thread		Full thread		16.00	6.10	19.05	9.65	22.35	12.45	25.40	15.75	28.45	18.80	31.75	21.84	35.05	25.15	38.10	28.45	41.15	31.50	44.45	34.54	50.80	41.15	57.15	47.24	63.50	53.85	69.85	59.94	76.20	66.55	82.55	72.64	88.90	79.25	95.25	85.34	101.60	91.95	107.95	98.30	114.30	104.65	120.65	110.74	120.65	110.74	127.00	117.35	133.35	123.44	139.70	130.05	146.05	136.14	152.40	142.75	158.75	149.10	165.10	155.45	171.45	161.54	177.80	168.15	184.15	174.24	190.50	180.85	196.85	186.94	203.20	193.55	209.55	199.64	215.90	206.25	241.30	231.65	266.70	257.05
9/16	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		19.05	8.38	22.35	11.43	25.40	14.73	28.45	19.05	31.75	21.08	35.05	24.38	38.10	27.43	41.15	30.73	47.75	37.08	53.85	43.43	60.45	49.78	66.55	56.13	73.15	62.48	79.25	68.83	85.85	75.18	91.95	81.53	98.55	87.88	104.65	94.23	111.25	100.58	117.35	106.93	117.35	106.93	123.95	113.28	130.05	119.63	136.65	125.98	142.75	132.08	149.35	138.68	155.45	145.03	162.05	151.38	168.15	157.73	174.75	164.08	180.85	170.43	187.45	176.78	193.55	183.13	200.15	189.48	206.25	195.83	212.85	202.18	238.25	227.58	263.65	252.98
5/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		19.05	7.62	22.35	10.67	25.40	13.97	28.45	17.02	31.75	20.32	35.05	23.37	38.10	26.67	44.45	33.02	50.80	39.37	57.15	45.72	63.50	52.07	69.85	58.42	76.20	64.77	82.55	71.12	88.90	77.47	95.25	83.82	101.60	90.17	107.95	96.52	114.30	102.87	114.30	102.87	120.65	109.22	127.00	115.57	133.35	121.92	139.70	128.27	146.05	134.62	152.40	140.97	158.75	147.32	165.10	153.67	171.45	160.02	177.80	166.37	184.15	172.72	190.50	179.07	196.85	185.42	203.20	191.77	209.55	198.12	234.95	223.52	260.35	248.92
3/4	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		28.45	17.02	31.75	20.32	35.05	23.37	38.10	26.67	38.10	25.40	44.45	31.75	50.80	38.10	57.15	44.45	63.50	50.80	69.85	57.15	76.20	63.50	82.55	69.85	88.90	76.20	95.25	82.55	101.60	88.90	107.95	95.25	107.95	95.25	114.30	101.60	120.65	107.95	127.00	114.30	133.35	120.65	139.70	127.00	146.05	133.35	152.40	139.70	158.75	146.05	165.10	152.40	171.45	158.75	177.80	165.10	184.15	171.45	190.50	177.80	196.85	184.15	203.20	190.50	228.60	215.90	254.00	241.30
7/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		25.40	12.70	28.45	15.75	31.75	19.05	31.75	17.53	38.10	23.88	44.45	30.23	50.80	36.58	57.15	42.93	63.50	49.28	69.85	55.63	76.20	61.98	82.55	68.33	88.90	74.68	95.25	81.03	101.60	87.38	101.60	87.38	107.95	93.73	114.30	100.08	120.65	106.43	127.00	112.78	133.35	119.13	139.70	125.48	146.05	131.83	152.40	138.18	158.75	144.53	165.10	150.88	171.45	157.23	177.80	163.58	184.15	170.18	190.50	176.28	196.85	182.63	222.25	208.03	247.65	233.43
1	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		22.35	8.13	25.40	11.18	25.40	9.65	31.75	15.75	38.10	22.35	44.45	28.45	50.80	35.05	57.15	41.15	63.50	47.75	69.85	53.85	76.20	60.45	82.55	66.55	88.90	73.15	95.25	79.25	95.25	79.25	101.60	85.85	107.95	92.20	114.30	98.55	120.65	104.65	127.00	111.25	133.35	117.60	139.70	123.95	146.05	130.05	152.40	136.65	158.75	142.75	165.10	149.35	171.45	155.45	177.80	162.05	184.15	168.15	190.50	174.75	215.90	200.15	241.30	225.55
1-1/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		31.75	13.72	38.10	20.07	44.45	26.42	50.80	32.77	57.15	39.12	63.50	45.47	69.85	51.82	76.20	58.17	82.55	64.52	88.90	70.87	88.90	70.87	95.25	77.22	101.60	83.57	107.95	89.92	114.30	96.27	120.65	102.62	127.00	108.97	133.35	115.32	139.70	121.67	146.05	128.02	152.40	134.37	158.75	140.72	165.10	147.07	171.45	153.42	177.80	159.77	184.15	166.12	209.55	191.52	234.95	216.92
1-1/4	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		31.75	13.72	38.10	20.07	44.45	26.42	50.80	32.77	57.15	39.12	63.50	45.47	69.85	51.82	76.20	58.17	82.55	64.52	82.55	64.52	88.90	70.87	95.25	77.22	101.60	83.57	107.95	89.92	114.30	96.27	120.65	102.62	127.00	108.97	133.35	115.32	139.70	121.67	146.05	128.02	152.40	134.37	158.75	140.72	165.10	147.07	171.45	153.42	177.80	159.77	203.20	185.17	228.60	210.57
1-3/8	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		38.10	20.07	44.45	26.42	50.80	32.77	57.15	39.12	63.50	45.47	69.85	51.82	76.20	58.17	82.55	64.52	82.55	64.52	88.90	70.87	95.25	77.22	101.60	83.57	107.95	89.92	114.30	96.27	120.65	102.62	127.00	108.97	133.35	115.32	139.70	121.67	146.05	128.02	152.40	134.37	158.75	140.72	165.10	147.07	171.45	153.42	196.85	178.82	222.25	204.22
1-1/2	Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		Full thread		38.10	17.02	44.45	23.37	50.80	29.72	57.15	36.07	63.50	42.42	69.85	48.77	69.85	48.77	76.20	55.12	82.55	61.47	88.90	67.82	95.25	74.17	101.60	80.52	107.95	86.87	114.30	93.22	120.65	99.57	127.00	105.92	133.35	112.27	139.70	118.62	146.05	124.97	152.40	131.32	158.75	137.67	165.10	144.02	190.50	169.42	215.90	194.82

ASME Material Specifications

ASTM A193/A193M Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for High Temperature or High Pressure Service and Other Special Purpose Applications
ASTM A307 Standard Specification for Carbon Steel Bolts and Studs, 60 000 PSI Tensile Strength
ASTM A449 Standard Specification for Hex Cap Screws, Bolts and Studs, Steel, Heat Treated, 120/105/90 ksi Minimum Tensile Strength
ASTM A453/A453M Standard Specification for Bolting, Stud Bolts, Screws, Nuts
ASTM A354 Standard Specification for Quenched and Tempered Alloy Steel Bolts, Studs, and Other Externally Threaded Fasteners
ASTM A320 Standard Specification for Alloy-Steel and Stainless Steel Bolting for Low-Temperature Service
ASTM A1082/A1082M Standard Specification for Bolting, Stud Bolts, Screws, Nuts
ASTM A1014/A1014M Standard Specification for UNS N07718 Bolting, Stud Bolts, Screws, Nuts
ASTM F468 Standard Specification for Nonferrous Bolts, Hex Cap Screws, and Studs
ASTM F593 Standard Specification for Stainless Steel Bolts, Hex Cap Screws, and Studs
ASTM F901 Aluminium Transmission Tower Bolts
ASTM F738 Stud Bolts, Screws
ASTM F1554 Anchor Bolts, Anchor Rods
ASTM F2281 Bolting, Stud Bolts, Screws, Hex Cap Screws, Threaded Rods
ASTM F3125 Heavy Hex Bolts, Screws, Studs