BS 916 Square Nut

Square Nuts

Nominal size D	Number of threads per inch		Approx. max. width across corners C		Thickness of nut E
	Number of threads per inch		Approx. max. width across corners C		Black		Faced one side
	B.S.W	B.S.F	Hexagon.	square.	max.	min.	max.
in.			in.	in.	in.	in.	in.
¼	20	26	0.51	0.63	0.220	0.200	0.200
⁵⁄₁₆	18	22	0.61	0.74	0.270	0.250	0.250
⅜	16	20	0.69	0.85	0.332	0.312	0.312
⁷⁄₁₆	14	18	0.82	1.00	0.395	0.375	0.375
½	12	16	0.95	1.16	0.467	0.437	0.437
⁹⁄₁₆	12	16	1.06	1.30	0.530	0.500	0.500
⅝	11	14	1.17	1.43	0.602	0.562	0.562
¾	10	12	1.39	1.70	0.728	0.687	0.687
⅞	9	11	1.50	1.84	0.810	0.750	0.750
1	8	10	1.71	2.09	0.935	0.875	0.875
1⅛	7	9	1.93	2.36	1.060	1.000	1.000
1¼	7	9	215	2.63	1.205	1.125	1.125
1⅜^a	6	8	2.37	2.90	1.330	1.250	1.250
1½	6	8	2.56	3.14	1.455	1.375	1.375
1⅝^a	5	8	2.78	3.41	1.580	1.500	1.500
1¾	5	7	2.98	3.65	1.725	1.625	1.625
2	4.5	7	3.19	3.90	1.850	1.750	1.750
2¼	4	6	3.64	4.45	1.975	1.875	1.875
2½	4	6	4.10	5.02	2.225	2.125	2.125
2¾	3.5	6	4.49	5.50	2.475	2.375	2.375
3	3.5	5	4.83	5.91	2.775	2.625	2.625
3¼^a	3.25	5	5.23	6.41	3.025	2.875	2.875
3½	3.25	4.5	5.60	6.86	3.275	3.125	3.125
3¾^a	3	4.5	5.98	7.33	3.525	3.375	3.375
4	3	4.5	6.41	7.85	3.775	3.625	3.625
4½	2.875	4	7.37	9.02	4.200	4.000	4.000
5	2.750	4	8.43	10.32	4.700	4.500	4.500
5½	2.625	4	9.64	11.81	5.200	5.000	5.000
6	2.500	4	10.91	13.36	5.700	5.500	5.500
^a To be dispensed with wherever possible. The dimensions of black lock nuts in the above table are designed to permit the product to be manufactured by either hot forging. cold forming or cold pressing, at the option of the manufacturer.