ASME B18.2.2 Square Machine Screw Nuts

Nominal Size	Basic Major Diameter of Thread	Width Across Flats, F			Width Across Corners		Thickness		Bearing Surface Runout to Thread Axis, FIM
		Basic	Min.	Max.	Square, G		Min.	Max.
		Basic	Min.	Max.	Min.	Max.	Min.	Max.
#0	1.524	3.969	3.810	3.962	5.232	5.613	1.092	1.270	0.127
#1	1.854	3.969	3.810	3.962	5.232	5.613	1.092	1.270	0.127
#2	2.184	4.763	4.572	4.775	6.274	6.731	1.448	1.676	0.152
#3	2.515	4.763	4.572	4.775	6.274	6.731	1.448	1.676	0.152
#4	2.845	6.350	6.121	6.350	8.407	8.992	2.210	2.489	0.229
#5	3.175	7.938	7.671	7.925	10.541	11.227	2.591	2.896	0.279
#6	3.505	7.938	7.671	7.925	10.541	11.227	2.591	2.896	0.279
#8	4.166	8.731	8.433	8.738	11.582	12.344	2.972	3.302	0.305
#10	4.826	9.525	9.195	9.525	12.624	13.462	2.972	3.302	0.330
#12	5.486	11.113	10.744	11.125	14.757	15.723	3.759	4.089	0.381
1⁄4	6.350	11.113	10.744	11.125	14.757	15.723	4.521	4.902	0.381
5⁄16	7.925	14.288	13.843	14.275	18.999	20.193	5.283	5.715	0.508
3⁄8	9.525	15.875	15.418	15.875	21.158	22.454	6.071	6.528	0.533

Nominal Size	Basic Major Diameter of Thread	Width Across Flats, F			Width Across Corners		Thickness		Bearing Surface Runout to Thread Axis, FIM
		Basic	Min.	Max.	Square, G		Min.	Max.
		Basic	Min.	Max.	Min.	Max.	Min.	Max.
#0	0.060	5⁄32	0.150	0.156	0.206	0.221	0.043	0.050	0.005
#1	0.073	5⁄32	0.150	0.156	0.206	0.221	0.043	0.050	0.005
#2	0.086	3⁄16	0.180	0.188	0.247	0.265	0.057	0.066	0.006
#3	0.099	3⁄16	0.180	0.188	0.247	0.265	0.057	0.066	0.006
#4	0.112	1⁄4	0.241	0.250	0.331	0.354	0.087	0.098	0.009
#5	0.125	5⁄16	0.302	0.312	0.415	0.442	0.102	0.114	0.011
#6	0.138	5⁄16	0.302	0.312	0.415	0.442	0.102	0.114	0.011
#8	0.164	11⁄32	0.332	0.344	0.456	0.486	0.117	0.130	0.012
#10	0.190	3⁄8	0.362	0.375	0.497	0.53	0.117	0.130	0.013
#12	0.216	7⁄16	0.423	0.438	0.581	0.619	0.148	0.161	0.015
1⁄4	0.250	7⁄16	0.423	0.438	0.581	0.619	0.178	0.193	0.015
5⁄16	0.312	9⁄16	0.545	0.562	0.748	0.795	0.208	0.225	0.020
3⁄8	0.375	5⁄8	0.607	0.625	0.833	0.884	0.239	0.257	0.021