SAE Bolts, Nuts & Washers

This table presents the most commonly used small to medium size varieties of SAE hardware. There are two general types of SAE bolts (sometimes referred to as machine screws). UNF (fine thread pitch) has more threads per inch than the same diameter bolt in the UNC (coarse thread pitch). Nut dimensions are maximums per SAE. Washer dimensions are for the regular size (vs. narrow or wide). All dimensions are in inches. Be aware that a search for hardware dimensions will yield variable results since many reported dimensions are manufacturers' production values, not necessarily the official SAE/ANSI values.

Note: For critical applications, consult official SAE/ANSI manuals to obtain dimensions.

Click here for a table of metric hardware sizes.

Size - Threads /Inch	Series	Tap Drill	Clearance Drill		Nut Points	Nut Flats	Washer I.D.	Washer O.D.
Size - Threads /Inch	Series	Tap Drill	Decimal (inches)	Number	Nut Points	Nut Flats	Washer I.D.	Washer O.D.
0-80	UNF	0.046	0.070	50	0.180	0.156	0.068	0.188
1-64	UNC	0.056	0.081	46	0.180	0.156	0.084	0.219
1-72	UNF	0.058	0.081	46	0.180	0.156	0.084	0.219
2-56	UNC	0.067	0.096	41	0.217	0.187	0.094	0.250
2-64	UNF	0.069	0.096	41	0.217	0.187	0.094	0.250
3-48	UNC	0.076	0.110	35	0.217	0.187	0.109	0.312
3-56	UNF	0.080	0.110	35	0.217	0.187	0.109	0.312
4-40	UNC	0.085	0.129	30	0.289	0.250	0.125	0.375
4-48	UNF	0.089	0.129	30	0.289	0.250	0.125	0.375
5-40	UNC	0.098	0.136	29	0.289	0.250	0.141	0.406
5-44	UNF	0.100	0.136	29	0.289	0.250	0.141	0.406
6-32	UNC	0.104	0.150	25	0.361	0.312	0.156	0.438
6-40	UNF	0.111	0.150	25	0.361	0.312	0.156	0.438
8-32	UNC	0.130	0.177	16	0.397	0.344	0.188	0.500
8-36	UNF	0.134	0.177	16	0.397	0.344	0.188	0.500
10-24	UNC	0.145	0.201	7	0.433	0.375	0.203	0.562
10-32	UNF	0.156	0.201	7	0.433	0.375	0.203	0.562
12-24	UNC	0.171	0.228	1	0.433	0.438	0.234	0.625
12-28	UNF	0.177	0.228	1	0.433	0.438	0.234	0.625
1/4-20	UNC	0.196	0.266	H	0.505	0.438	0.281	0.734
1/4-28	UNF	0.211	0.266	H	0.505	0.438	0.281	0.734
5/16-18	UNC	0.252	0.332	Q	0.577	0.500	0.344	0.875
5/16-24	UNF	0.267	0.332	Q	0.577	0.500	0.344	0.875
3/8-16	UNC	0.307	0.397	X	0.650	0.562	0.406	1.000
3/8-24	UNF	0.330	0.397	X	0.650	0.562	0.406	1.000
7/16-14	UNC	0.360	0.469	15/32	0.794	0.688	0.469	1.125
7/16-20	UNF	0.383	0.469	15/32	0.794	0.688	0.469	1.125
1/2-13	UNC	0.417	0.531	17/32	0.866	0.750	0.531	1.250
1/2-20	UNF	0.446	0.531	17/32	0.866	0.750	0.531	1.250
9/16-12	UNC	0.472	0.594	19/32	1.010	0.875	0.594	1.469
9/16-18	UNF	0.502	0.594	19/32	1.010	0.875	0.594	1.469
5/8-11	UNC	0.527	0.656	21/32	1.083	0.938	0.656	1.750
5/8-18	UNF	0.565	0.656	21/32	1.083	0.938	0.656	1.750
3/4-10	UNC	0.642	0.781	25/32	1.299	1.125	0.812	2.000
3/4-16	UNF	0.682	0.781	25/32	1.299	1.125	0.812	2.000
7/8-9	UNC	0.755	0.906	29/32	1.516	1.312	0.938	2.250
7/8-14	UNF	0.798	0.906	29/32	1.516	1.312	0.938	2.250
1-8	UNC	0.865	1.031	1 1/32	1.732	1.500	1.062	2.500
1-12	UNF	0.910	1.031	1 1/32	1.732	1.500	1.062	2.500
1-14	UN		1.031	1 1/32	1.732	1.500	1.062	2.500
1 1/8-7	UNC	0.970	1.156	1 5/32	1.949	1.688	1.188	2.750
1 1/8-8	UN		1.156	1 5/32	1.949	1.688	1.188	2.750
1 1/8-12	UNF	1.035	1.156	1 5/32	1.949	1.688	1.188	2.750
1 1/4-7	UNC	1.095	1.281	1 9/32	2.165	1.875	1.310	3.000
1 1/4-8	UN		1.281	1 9/32	2.165	1.875	1.310	3.000
1 1/4-12	UNF	1.160	1.281	1 9/32	2.165	1.875	1.310	3.000
1 3/8-6	UNC	1.195	1.406	1 13/32	2.382	2.062	1.438	3.250
1 3/8-8	UN		1.406	1 13/32	2.382	2.062	1.438	3.250
1 3/8-12	UNF	1.285	1.406	1 13/32	2.382	2.062	1.438	3.250
1 1/2-6	UNC	1.320	1.531	1 17/32	2.598	2.250	1.562	3.500
1 1/2-8	UN		1.531	1 17/32	2.598	2.250	1.562	3.500
1 1/2-12	UNC	1.410	1.531	1 17/32	2.598	2.250	1.562	3.500
1 5/8-8	UN		1.656	1 21/32	2.815	2.438	1.750	3.750
1 3/4-5	UNC	1.534	1.781	1 25/32	3.031	2.625	1.875	4.000
1 3/4-8	UN		1.781	1 25/32	3.031	2.625	1.875	4.000
1 7/8-8 2-4 1/2 2-8 2 1/4-4.5 2 1/4-8	UN UNC UN UNC UN
2 1/2-4 2 1/2-8 2 3/4-4 2 3/4-8 3-4	UNC UN UNC UN UNC
3-8 3 1/4-4 3 1/4-8 3 1/2-4 3 1/2-8	UN UNC UN UNC UN
3 3/4-4 3 3/4-8 4-4 4-8	UNC UN UNC UN

1) See Drill Sizes page for cross reference.
2) Nut Points is the distance between opposite corners of hex nuts.
3) Nut Flats is the distance between opposite sides of hex nuts.

Webmaster: Kirt Blattenberger, BSEE, UVM 1989