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ASME B18.16.6 – Dimensions Chart

ASME B18.16.6 is the American National Standard for Inch Series prevailing torque locknuts, the go-to reference for fasteners designed to stay secure under vibration. This standard provides essential dimensional and performance data for two primary categories: nylon insert locknuts (styles NE, NTE, NU, NTU, NM, NTM, and hex flange) and all-metal locknuts (hex and hex flange styles). Use the dimension charts below to find full specifications—including width across flats, thickness, hex height, and flange diameters—for all recognized styles.

Dimensions & Size Chart

Style NE Nyloc Nut Dimensions
Nut Size		1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4	7/8	1	1-1/8	1-1/4	1-3/8	1-1/2
A	Min	0.43	0.489	0.551	0.616	0.736	0.861	0.922	1.052	1.239	1.427	1.614	1.801	1.973	2.159
A	Max	0.439	0.502	0.564	0.627	0.752	0.877	0.94	1.064	1.252	1.44	1.627	1.815	2.008	2.197
B	Min	0.482	0.552	0.622	0.698	0.837	0.978	1.051	1.191	1.403	1.615	1.826	2.038	2.232	2.444
C	Min	0.298	0.329	0.438	0.438	0.579	0.626	0.735	0.86	0.969	1.016	1.141	1.36	1.547	1.578
C	Max	0.328	0.359	0.468	0.468	0.609	0.656	0.765	0.89	0.999	1.078	1.203	1.422	1.609	1.64
D	Min	0.225	0.25	0.335	0.324	0.464	0.469	0.593	0.742	0.79	0.825	0.93	1.125	1.282	1.313

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal nut, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the nut measured from point to point, ensuring enough clearance for the tool to rotate within an assembly.
C – Thickness: The total vertical height of the nyloc nut, including the raised collar that houses the nylon locking insert.
D – Height: The height of the standard hexagonal portion of the nut, representing the primary load-bearing area before the locking feature.

Style NTE Nyloc Nut Dimensions
Nut Size		1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4	7/8	1	1-1/8	1-1/4	1-3/8	1-1/2
A	Min	0.43	0.489	0.551	0.616	0.736	0.861	0.922	1.052	1.239	1.427	1.614	1.801	1.973	2.159
A	Max	0.439	0.502	0.564	0.627	0.752	0.877	0.94	1.064	1.252	1.44	1.627	1.815	2.008	2.197
B	Min	0.482	0.552	0.622	0.698	0.837	0.978	1.051	1.191	1.403	1.615	1.826	2.038	2.232	2.444
C	Min	0.188	0.235	0.251	0.298	0.298	0.344	0.376	0.391	0.454	0.516	0.61	0.703	0.759	0.766
C	Max	0.218	0.265	0.281	0.328	0.328	0.374	0.406	0.421	0.484	0.578	0.672	0.765	0.821	0.828
D	Min	0.125	0.158	0.15	0.225	0.19	0.225	0.265	0.288	0.34	0.405	0.5	0.523	0.493	0.565

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal nut, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the nut measured from point to point, ensuring enough clearance for the tool to rotate within an assembly.
C – Thickness: The total vertical height of the nyloc nut, including the raised collar that houses the nylon locking insert.
D – Height: The height of the standard hexagonal portion of the nut, representing the primary load-bearing area before the locking feature.

Style NU Nyloc Nut Dimensions
Nut Size		1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4	7/8	1	1-1/8	1-1/4	1-3/8	1-1/2	1-5/8	1-3/4	1-7/8	2	2-1/4	2-1/2	2-3/4	3
A	Min	0.489	0.551	0.675	0.736	0.861	0.922	1.045	1.231	1.417	1.602	1.788	1.973	2.159	2.344	2.53	2.715	2.901	3.086	3.457	3.875	3.875	4.5
A	Max	0.506	0.566	0.691	0.754	0.879	0.942	1.067	1.255	1.444	1.632	1.82	2.008	2.197	2.384	2.572	2.762	2.95	3.137	3.514	4.015	4.015	4.64
B	Min	0.556	0.624	0.763	0.829	0.969	1.037	1.175	1.382	1.589	1.796	2.002	2.209	2.416	2.622	2.886	3.035	3.242	3.449	3.862	4.618	4.618	5.102
C	Min	0.36	0.423	0.532	0.579	0.688	0.782	0.844	0.985	1.11	1.25	1.407	1.61	1.766	1.891	2.11	2.25	2.296	2.343	2.75	3.078	3.078	3.578
C	Max	0.39	0.453	0.562	0.609	0.718	0.812	0.874	1.015	1.14	1.312	1.469	1.672	1.828	1.953	2.172	2.376	2.422	2.469	2.876	3.204	3.204	3.704
D	Min	0.29	0.335	0.392	0.464	0.544	0.655	0.677	0.79	0.883	1	1.096	1.25	1.376	1.413	1.637	1.83	1.875	1.75	2.063	2.475	2.35	2.75

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal nut, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the nut measured from point to point, ensuring enough clearance for the tool to rotate within an assembly.
C – Thickness: The total vertical height of the nyloc nut, including the raised collar that houses the nylon locking insert.
D – Height: The height of the standard hexagonal portion of the nut, representing the primary load-bearing area before the locking feature.

Style NTU Nyloc Nut Dimensions
Nut Size		1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4	7/8	1	1-1/8	1-1/4	1-3/8	1-1/2	1-3/4	1-7/8	2	2-1/4	2-1/2	2-3/4	3
A	Min	0.492	0.553	0.679	0.741	0.865	0.928	1.052	1.239	1.427	1.614	1.801	1.973	2.159	2.344	2.715	3.086	3.086	3.457	3.875	3.875	4.5
A	Max	0.502	0.564	0.69	0.752	0.877	0.94	1.064	1.252	1.44	1.627	1.814	2.008	2.197	2.384	2.762	3.137	3.137	3.514	4.015	4.015	4.64
B	Min	0.552	0.622	0.766	0.837	0.978	1.051	1.191	1.403	1.615	1.826	2.038	2.232	2.444	2.622	3.075	3.497	3.497	3.918	4.393	4.393	5.102
C	Min	0.266	0.298	0.391	0.423	0.516	0.548	0.594	0.688	0.766	0.86	0.938	1.078	1.157	1.282	1.406	1.609	1.609	1.875	2.124	2.124	2.662
C	Max	0.296	0.328	0.421	0.453	0.546	0.578	0.624	0.718	0.796	0.922	1	1.14	1.219	1.344	1.532	1.735	1.735	2.001	2.25	2.25	2.788
D	Min	0.194	0.212	0.251	0.316	0.36	0.421	0.428	0.488	0.535	0.6	0.627	0.72	0.767	0.81	0.986	1.016	1.016	1.179	1.523	1.523	2.075

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal nut, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the nut measured from point to point, ensuring enough clearance for the tool to rotate within an assembly.
C – Thickness: The total vertical height of the nyloc nut, including the raised collar that houses the nylon locking insert.
D – Height: The height of the standard hexagonal portion of the nut, representing the primary load-bearing area before the locking feature.

Style NM Nyloc Nut Dimensions
Nut Size		#2	#4	#6	#8	#10	#12
A	Min	0.243	0.243	0.305	0.336	0.367	0.43
A	Max	0.251	0.251	0.313	0.345	0.376	0.439
B	Min	0.268	0.268	0.339	0.374	0.41	0.482
C	Min	0.133	0.133	0.168	0.219	0.229	0.298
C	Max	0.153	0.153	0.188	0.239	0.249	0.328
D	Min	0.081	0.081	0.103	0.14	0.14	0.225

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal nut, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the nut measured from point to point, ensuring enough clearance for the tool to rotate within an assembly.
C – Thickness: The total vertical height of the nyloc nut, including the raised collar that houses the nylon locking insert.
D – Height: The height of the standard hexagonal portion of the nut, representing the primary load-bearing area before the locking feature.

Style NTM Nyloc Nut Dimensions
Nut Size		#2	#3	#4	#5	#6	#8	#10	#12
A	Min	0.243	0.243	0.243	0.243	0.305	0.336	0.367	0.43
A	Max	0.251	0.251	0.251	0.251	0.313	0.345	0.376	0.439
B	Min	0.268	0.268	0.268	0.268	0.339	0.374	0.41	0.482
C	Min	0.094	0.094	0.094	0.094	0.11	0.157	0.157	0.188
C	Max	0.124	0.124	0.124	0.124	0.14	0.187	0.187	0.218
D	Min	0.081	0.081	0.103	0.14	0.14	0.225	0.081	0.081

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal nut, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the nut measured from point to point, ensuring enough clearance for the tool to rotate within an assembly.
C – Thickness: The total vertical height of the nyloc nut, including the raised collar that houses the nylon locking insert.
D – Height: The height of the standard hexagonal portion of the nut, representing the primary load-bearing area before the locking feature.

Flanged Nyloc Nut Dimensions
Nut Size		1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4
A	Min	0.428	0.489	0.551	0.675	0.736	0.861	0.922	1.088
A	Max	0.4385	0.502	0.5645	0.6895	0.752	0.877	0.9395	1.127
B	Min	0.488	0.557	0.628	0.768	0.84	0.982	1.051	1.24
B	Max	0.505	0.577	0.65	0.794	0.866	1.01	1.083	1.299
C	Max	0.3	0.365	0.425	0.495	0.555	0.625	0.69	0.825
D	Min	0.14	0.17	0.2	0.23	0.26	0.29	0.32	0.38
E	Min	0.484	0.602	0.73	0.846	0.982	1.101	1.23	1.472
G	Min	0.04	0.05	0.06	0.07	0.08	0.09	0.1	0.11
R	Max	0.01	0.01	0.02	0.02	0.02	0.03	0.03	0.03
F	Max	0.56	0.68	0.81	0.93	1.07	1.19	1.33	1.585

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal section, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the hexagonal portion measured from point to point, ensuring enough clearance for the tool to rotate.
C – Thickness: The total vertical height of the flanged nyloc nut, including the flange and the raised collar housing the nylon locking insert.
D – Wrenching Height: The height of the flat hexagonal sides available for tool engagement, excluding the flange and the locking collar.
E – Diameter of Bearing Surface: The actual contact area on the underside of the flange that meets the mating surface to distribute clamping pressure.
F – Flange Diameter: The total outer diameter of the integrated washer base.
G – Flange Thickness: The vertical thickness of the integrated washer base at its outer edge.
R – Top Flange Radius: The curved transition between the top of the flange and the start of the hexagonal wrenching flats.

Prevailing Torque All Metal Hex Nut Dimensions
Nut Size		#4	#6	#8	#10	#12	1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4	7/8	1	1-1/8	1-1/4	1-3/8	1-1/2
A	Min	0.241	0.302	0.332	0.362	0.423	0.428	0.489	0.551	0.675	0.736	0.861	0.922	1.088	1.269	1.45	1.631	1.812	1.994	2.175
A	Max	0.251	0.313	0.345	0.376	0.438	0.4385	0.502	0.5645	0.6895	0.752	0.877	0.9395	1.127	1.3145	1.502	1.6895	1.877	2.0645	2.252
B	Min	0.275	0.344	0.378	0.413	0.482	0.488	0.557	0.628	0.768	0.84	0.982	1.051	1.24	1.447	1.653	1.859	2.066	2.273	2.48
B	Max	0.289	0.361	0.397	0.433	0.505	0.505	0.577	0.65	0.794	0.866	1.01	1.083	1.299	1.516	1.732	1.949	2.165	2.382	2.598
C	Min	0.087	0.102	0.117	0.117	0.148	0.212	0.258	0.32	0.365	0.427	0.473	0.535	0.617	0.724	0.831	0.939	1.03	1.138	1.245
C	Max	0.163	0.171	0.191	0.241	0.241	0.288	0.336	0.415	0.463	0.573	0.621	0.731	0.827	0.922	1.018	1.176	1.272	1.399	1.526
D	Min	0.066	0.075	0.083	0.083	0.103	0.145	0.166	0.198	0.223	0.262	0.286	0.329	0.382	0.45	0.513	0.576	0.628	0.681	0.757

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal nut, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the nut measured from point to point, ensuring enough clearance for the tool to rotate within an assembly.
C – Thickness: The total vertical height of the nyloc nut, including the raised collar that houses the nylon locking insert.
D – Height: The height of the standard hexagonal portion of the nut, representing the primary load-bearing area before the locking feature.

Prevailing Torque All Metal Flanged Hex Nut Dimensions
Nut Size		1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4
A	Min	0.428	0.489	0.551	0.675	0.736	0.861	0.922	1.088
A	Max	0.4385	0.502	0.5645	0.6895	0.752	0.877	0.9395	1.127
B	Min	0.448	0.557	0.628	0.768	0.84	0.982	1.051	1.24
B	Max	0.505	0.577	0.65	0.794	0.866	1.01	1.083	1.299
C	Max	0.3	0.365	0.425	0.495	0.555	0.625	0.69	0.825
D	Min	0.14	0.17	0.2	0.23	0.26	0.29	0.32	0.38
E	Min	0.484	0.602	0.73	0.846	0.982	1.101	1.23	1.472
G	Min	0.04	0.05	0.06	0.07	0.08	0.09	0.1	0.11
R	Max	0.01	0.01	0.02	0.02	0.02	0.03	0.03	0.03
F	Max	0.56	0.68	0.81	0.93	1.07	1.19	1.33	1.585

Note: All measurements are in inches

Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.

Legend

A – Width Across Flats: The distance between two parallel flat surfaces of the hexagonal section, used to identify the correct wrench or socket size for installation.
B – Width Across Corners: The maximum diameter of the hexagonal portion measured from point to point, ensuring enough clearance for the tool to rotate.
C – Thickness: The total vertical height of the flanged nyloc nut, including the flange and the raised collar housing the nylon locking insert.
D – Wrenching Height: The height of the flat hexagonal sides available for tool engagement, excluding the flange and the locking collar.
E – Diameter of Bearing Surface: The actual contact area on the underside of the flange that meets the mating surface to distribute clamping pressure.
F – Flange Diameter: The total outer diameter of the integrated washer base.
G – Flange Thickness: The vertical thickness of the integrated washer base at its outer edge.
R – Top Flange Radius: The curved transition between the top of the flange and the start of the hexagonal wrenching flats.