ASME B18.2.1 Square Head Bolts

Dimensions of Square Head Bolts
														Thread Length for Bolt Leng ths, LT (See Para. 3.7)
Nominal Size or Basic Product Diameter		Full-Size Body Diameter, E (See Paras. 3.4 and 3.5)		Width Across Flats, F (See Para. 2.1.2)			Width Across Corners, G		Head Height, H			Radius of Fillet, R		6 in. and Shorter	Over 6 in.
Nominal Size or Basic Product Diameter		Max.	Min.	Basic	Max.	Min.	Max.	Min.	Basic	Max.	Min.	Max.	Min.	Nom.	Nom.
1/4	0.25	0.26	0.237	3/8	0.375	0.362	0.53	0.498	11/64	0.188	0.156	0.03	0.01	0.75	1
5/16	0.3125	0.324	0.298	1/2	0.5	0.484	0.707	0.665	13/64	0.22	0.186	0.03	0.01	0.875	1.125
3/8	0.375	0.388	0.36	9/16	0.562	0.544	0.795	0.747	1/4	0.268	0.232	0.03	0.01	1	1.25
7/16	0.4375	0.452	0.421	5/8	0.625	0.603	0.884	0.828	19/64	0.316	0.278	0.03	0.01	1.125	1.375
1/2	0.5	0.515	0.482	3/4	0.75	0.725	1.061	0.995	21/64	0.348	0.308	0.03	0.01	1.25	1.5
5/8	0.625	0.642	0.605	1 5/16	0.938	0.906	1.326	1.244	27/64	0.444	0.4	0.06	0.02	1.5	1.75
3/4	0.75	0.768	0.729	1 1/8	1.125	1.088	1.591	1.494	1/2	0.524	0.476	0.06	0.02	1.75	2
7/8	0.875	0.895	0.852	1 5/16	1.312	1.269	1.856	1.742	19/32	0.62	0.568	0.06	0.02	2	2.25
1	1	1.022	0.976	1 1/2	1.5	1.45	2.121	1.991	21/32	0.684	0.628	0.09	0.03	2.25	2.5
1 1/8	1.125	1.149	1.098	1 11/16	1.688	1.631	2.386	2.239	3/4	0.78	0.72	0.09	0.03	2.5	2.75
1 1/4	1.25	1.277	1.223	1 7/8	1.875	1.812	2.652	2.489	27/32	0.876	0.812	0.09	0.03	2.75	3
1 3/8	1.375	1.404	1.345	2 1/16	2.062	1.994	2.917	2.738	29/32	0.94	0.872	0.09	0.03	3	3.25
1 1/2	1.5	1.531	1.47	2 1/4	2.25	2.175	3.182	2.986	1	1.036	0.964	0.09	0.03	3.25	3.5