ASME B18.2.1 Hex Cap Screws

Scope

ASME B18.2.1 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 Hex Cap Screws Dimensions (mm)

Nominal Size or Basic Product Diameter		Body Diameter, E		Width Across Flats, F			Width Across Corners, G		Head Height, H			Minimum Wrenching Height, J	Nominal Thread Length for Screw Lengths, LT		Transition Thread Length, Y Reference	Maximum Total Runout of Bearing Surface FIM
Nominal Size or Basic Product Diameter		Max.	Min.	Basic	Max.	Min.	Max.	Min.	Basic	Max.	Min.	Minimum Wrenching Height, J	150mm (6") and Shorter	Over 150mm (6")	Transition Thread Length, Y Reference	Maximum Total Runout of Bearing Surface FIM
1/4	0.2500	6.350	6.223	11.113	11.125	10.871	12.827	12.395	3.969	4.140	3.810	2.692	19.050	25.400	6.350	0.254
5/16	0.3125	7.938	7.785	12.700	12.700	12.421	14.656	14.148	5.159	5.359	4.953	3.556	22.225	28.575	7.061	0.279
3/8	0.3750	9.525	9.373	14.288	14.275	13.995	16.510	15.951	5.953	6.172	5.740	4.064	25.400	31.750	7.925	0.305
7/16	0.4375	11.113	10.935	15.875	15.875	15.545	18.339	17.729	7.144	7.391	6.909	4.953	28.575	34.925	9.068	0.330
1/2	0.5000	12.700	12.522	19.050	19.050	18.694	21.996	21.336	7.938	8.204	7.671	5.461	31.750	38.100	9.779	0.356
9/16	0.5625	14.288	14.084	20.638	20.625	20.269	23.825	23.114	9.128	9.423	8.839	6.350	34.925	41.275	10.592	0.381
5/8	0.6250	15.875	15.672	23.813	23.825	23.419	27.508	26.695	9.922	10.236	9.601	6.833	38.100	44.450	11.557	0.432
3/4	0.7500	19.050	18.821	28.575	28.575	27.940	32.995	31.852	11.906	12.268	11.557	8.230	44.450	50.800	12.700	0.508
7/8	0.8750	22.225	21.996	33.338	33.325	32.639	38.506	37.211	13.891	14.300	13.487	9.601	50.800	57.150	14.122	0.584
1	1.0000	25.400	25.146	38.100	38.100	37.313	43.993	42.545	15.478	15.926	15.011	10.566	57.150	63.500	15.875	0.660
1 1/8	1.1250	28.575	28.296	42.863	42.875	41.427	49.505	47.219	17.463	18.237	16.713	11.709	63.500	69.850	18.136	0.737
1 1/4	1.2500	31.750	31.471	47.625	47.625	46.025	54.991	52.476	19.844	20.650	19.025	13.462	69.850	76.200	18.136	0.838
1 3/8	1.3750	34.925	34.620	52.388	52.375	50.648	60.503	57.734	21.431	22.301	20.574	14.453	76.200	82.550	21.158	0.914
1 1/2	1.5000	38.100	37.795	57.150	57.150	55.245	65.989	62.992	23.813	24.740	22.911	16.256	82.550	88.900	21.158	0.991
1 5/8	1.6250	41.275	40.970	61.913	61.925	59.842	71.501	68.224	25.400	26.365	24.435	17.628	88.900	95.250	23.089	1.092
1 3/4	1.7500	44.450	44.145	66.675	66.675	64.465	76.987	73.482	27.781	28.804	26.772	18.999	95.250	101.600	25.400	1.168
1 7/8	1.8750	47.625	47.320	71.438	71.425	69.063	82.499	78.715	29.369	30.429	28.296	20.371	101.600	107.950	25.400	1.245
2	2.0000	50.800	50.495	76.200	76.200	73.660	87.986	83.972	30.956	32.080	29.845	20.955	107.950	114.300	28.219	1.321
2 1/4	2.2500	57.150	56.845	85.725	85.725	82.855	98.984	94.463	34.925	36.144	33.706	23.698	...	127.000	28.219	1.499
2 1/2	2.5000	63.500	63.195	95.250	95.250	92.075	109.982	104.978	40.481	40.208	37.567	26.467	...	139.700	31.750	1.651
2 3/4	2.7500	69.850	69.545	104.775	104.775	101.295	120.980	115.468	42.863	44.298	41.453	29.235	...	152.400	31.750	1.829
3	3.0000	76.200	75.895	114.300	114.300	110.490	131.978	125.959	47.625	49.149	46.101	32.766	...	165.100	31.750	2.007

ASME B18.2.1 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 Hex Cap Screws Grip Gaging 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 Hex Cap Screws Dimensions (Inch)

Nominal Size or Basic Product Diameter		Body Diameter, E		Width Across Flats, F			Width Across Corners, G		Head Height, H			Minimum Wrenching Height, J	Nominal Thread Length for Screw Lengths, LT		Transition Thread Length, Y	Maximum Total Runout of Bearing Surface FIM
Nominal Size or Basic Product Diameter		Max.	Min.	Basic	Max.	Min.	Max.	Min.	Basic	Max.	Min.	Minimum Wrenching Height, J	6 in. and Shorter	Over 6 in.	Transition Thread Length, Y	Maximum Total Runout of Bearing Surface FIM
1/4	0.2500	0.2500	0.2450	7/16	0.438	0.428	0.505	0.488	5/32	0.163	0.150	0.106	0.750	1.000	0.250	0.010
5/16	0.3125	0.3125	0.3065	1/2	0.500	0.489	0.577	0.557	13/64	0.211	0.195	0.140	0.875	1.125	0.278	0.011
3/8	0.3750	0.3750	0.3690	9/16	0.562	0.551	0.650	0.628	15/64	0.243	0.226	0.160	1.000	1.250	0.312	0.012
7/16	0.4375	0.4375	0.4305	5/8	0.625	0.612	0.722	0.698	9/32	0.291	0.272	0.195	1.125	1.375	0.357	0.013
1/2	0.5000	0.5000	0.4930	3/4	0.750	0.736	0.866	0.840	5/16	0.323	0.302	0.215	1.250	1.500	0.385	0.014
9/16	0.5625	0.5625	0.5545	13/16	0.812	0.798	0.938	0.910	23/64	0.371	0.348	0.250	1.375	1.625	0.417	0.015
5/8	0.6250	0.6250	0.6170	15/16	0.938	0.922	1.083	1.051	25/64	0.403	0.378	0.269	1.500	1.750	0.455	0.017
3/4	0.7500	0.7500	0.7410	1 1/8	1.125	1.100	1.299	1.254	15/32	0.483	0.455	0.324	1.750	2.000	0.500	0.020
7/8	0.8750	0.8750	0.8660	1 5/16	1.312	1.285	1.516	1.465	35/64	0.563	0.531	0.378	2.000	2.250	0.556	0.023
1	1.0000	1.0000	0.9900	1 1/2	1.500	1.469	1.732	1.675	39/64	0.627	0.591	0.416	2.250	2.500	0.625	0.026
1 1/8	1.1250	1.1250	1.1140	1 11/16	1.688	1.631	1.949	1.859	11/16	0.718	0.658	0.461	2.500	2.750	0.714	0.029
1 1/4	1.2500	1.2500	1.2390	1 7/8	1.875	1.812	2.165	2.066	25/32	0.813	0.749	0.530	2.750	3.000	0.714	0.033
1 3/8	1.3750	1.3750	1.3630	2 1/16	2.062	1.994	2.382	2.273	27/32	0.878	0.810	0.569	3.000	3.250	0.833	0.036
1 1/2	1.5000	1.5000	1.4880	2 1/4	2.250	2.175	2.598	2.480	15/16	0.974	0.902	0.640	3.250	3.500	0.833	0.039
1 5/8	1.6250	1.6250	1.6130	2 7/16	2.438	2.356	2.815	2.686	1	1.038	0.962	0.694	3.500	3.750	0.909	0.043
1 3/4	1.7500	1.7500	1.7380	2 5/8	2.625	2.538	3.031	2.893	1 3/32	1.134	1.054	0.748	3.750	4.000	1.000	0.046
1 7/8	1.8750	1.8750	1.8630	2 13/16	2.812	2.719	3.248	3.099	1 5/32	1.198	1.114	0.802	4.000	4.250	1.000	0.049
2	2.0000	2.0000	1.9880	3	3.000	2.900	3.464	3.306	1 7/32	1.263	1.175	0.825	4.250	4.500	1.111	0.052
2 1/4	2.2500	2.2500	2.2380	3 3/8	3.375	3.262	3.897	3.719	1 3/8	1.423	1.327	0.933	...	5.000	1.111	0.059
2 1/2	2.5000	2.5000	2.4880	3 3/4	3.750	3.625	4.330	4.133	1 17/32	1.583	1.479	1.042	...	5.500	1.250	0.065
2 3/4	2.7500	2.7500	2.7380	4 1/8	4.125	3.988	4.763	4.546	1 11/16	1.744	1.632	1.151	...	6.000	1.250	0.072
3	3.0000	3.0000	2.9880	4 1/2	4.500	4.350	5.196	4.959	1 7/8	1.935	1.815	1.290	...	6.500	1.250	0.079

ASME B18.2.1 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 Hex Cap Screws Grip Gaging 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