Coarse Thread Sizes

National Coarse Thread Sizes (UNC/UNRC) Measured in Inches
Nominal Size	Major Diameter	Threads/inch	Basic Pitch Diameter	Minor Diameter	Lead Angle at Basic Pitch Diameter		Height of Fundamental Triangle	Tensile Stress Area
					(Degrees)	(Min)		(square inches)
#1	0.073	64	0.063	0.056	4	31	0.01353	0.003
#2	0.086	56	0.074	0.067	4	22	0.01547	0.004
#3	0.099	48	0.086	0.076	4	26	0.01804	0.005
#4	0.112	40	0.096	0.085	4	45	0.02165	0.006
#5	0.125	40	0.109	0.098	4	11	0.02165	0.008
#6	0.138	32	0.118	0.104	4	50	0.02706	0.009
#8	0.164	32	0.144	0.130	3	58	0.02706	0.014
#10	0.190	24	0.163	0.145	4	39	0.03608	0.018
#12	0.216	24	0.189	0.171	4	1	0.03608	0.024
1/4	0.250	20	0.218	0.196	4	11	0.04330	0.032
5/16	0.313	18	0.276	0.252	3	40	0.04811	0.052
3/8	0.375	16	0.334	0.307	3	24	0.05413	0.078
7/16	0.438	14	0.391	0.360	3	20	0.06186	0.106
1/2	0.500	13	0.450	0.417	3	7	0.06662	0.142
9/16	0.563	12	0.508	0.472	2	59	0.07217	0.182
5/8	0.625	11	0.566	0.527	2	56	0.07873	0.226
3/4	0.750	10	0.685	0.642	2	40	0.08660	0.334
7/8	0.875	9	0.803	0.755	2	31	0.09623	0.462
1	1.000	8	0.919	0.865	2	29	0.10825	0.606
1 1/8	1.125	7	1.032	0.941	2	31	0.12372	0.763
1 1/4	1.250	7	1.157	1.095	2	15	0.12372	0.969
1 3/8	1.375	6	1.267	1.195	2	24	0.14434	1.155
1 1/2	1.500	6	1.392	1.320	2	11	0.14434	1.405
1 3/4	1.750	5	1.620	1.534	2	15	0.17321	1.900
2	2.000	4 1/2	1.856	1.759	2	11	0.19245	2.500
2 1/4	2.250	4 1/2	2.106	2.009	1	55	0.19245	3.250
2 1/2	2.500	4	2.338	2.229	1	57	0.21651	4.000
2 3/4	2.750	4	2.588	2.479	1	46	0.21651	4.930
3	3.000	4	2.838	2.729	1	36	0.21651	5.970
3 1/4	3.250	4	3.088	2.979	1	29	0.21651	7.100
3 1/2	3.500	4	3.338	3.229	1	22	0.21651	8.330
3 3/4	3.750	4	3.588	3.479	1	16	0.21651	9.660
4	4.000	4	3.838	3.729	1	11	0.21651	11.080
Standards set by American Society of Mechanical Engineers

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National Coarse Thread Sizes (UNC/UNRC)