Standard Series Internal Unified Screw Threads Class 2
Unified Screw Thread	Min Tap Drill Size	Tap Drill	Max Tap Drill Size	Major Diameter	Clearance Drill
Unified Screw Thread	Min Tap Drill Size	Tap Drill	Max Tap Drill Size	Major Diameter	Drill	Size
0-80 UNF	0.0465	3/64	0.0514	0.0600	1/16	0.0625
1-64 UNC	0.0561	#53	0.0623	0.0730	#49	0.0730
1-72 UNF	0.0580	#53	0.0635	0.0730	#49	0.0730
2-56 UNC	0.0667	#50	0.0737	0.0860	#44	0.0860
2-64 UNF	0.0691	#50	0.0753	0.0860	#44	0.0860
3-48 UNC	0.0764	#47	0.0845	0.0990	#39	0.0995
3-56 UNF	0.0797	#46	0.0865	0.0990	#39	0.0995
4-40 UNC	0.0849	#43	0.0939	0.1120	#33	0.1130
4-48 UNF	0.0894	#42	0.0968	0.1120	#33	0.1130
5-40 UNC	0.0979	#39	0.1062	0.1250	1/8	0.1250
5-44 UNF	0.1004	#38	0.1079	0.1250	1/8	0.1250
6-32 UNC	0.104	#36	0.114	0.1380	#28	0.1405
6-40 UNF	0.111	#34	0.119	0.1380	#28	0.1405
8-32 UNC	0.130	#29	0.139	0.1640	#19	0.1660
8-36 UNF	0.134	#29	0.142	0.1640	#19	0.1660
10-24 UNC	0.145	#26	0.156	0.1900	#11	0.1910
10-32 UNF	0.156	5/32	0.164	0.1900	#11	0.1910
12-24 UNC	0.171	11/64	0.181	0.2160	7/32	0.2188
12-28 UNF	0.177	#16	0.186	0.2160	7/32	0.2188
1/4-20 UNC	0.196	#9	0.207	0.2500	E, 1/4	0.2500
1/4-28 UNF	0.211	#3	0.220	0.2500	E, 1/4	0.2500
5/16-18 UNC	0.252	F	0.265	0.3125	5/16	0.3125
5/16-24 UNF	0.267	I	0.277	0.3125	5/16	0.3125
3/8-16 UNC	0.307	5/16	0.321	0.3750	3/8	0.3750
3/8-24 UNF	0.330	Q	0.340	0.3750	3/8	0.3750

Standard Series Internal Unified Screw Threads Class 2
Unified Screw Thread	Min Tap Drill Size	Tap Drill	Max Tap Drill Size	Major Diameter	Clearance Drill
Unified Screw Thread	Min Tap Drill Size	Tap Drill	Max Tap Drill Size	Major Diameter	Drill	Size
7/16-14 UNC	0.360	U	0.376	0.4375	7/16	0.4375
7/16-20 UNF	0.383	W	0.395	0.4375	7/16	0.4375
1/2-13 UNC	0.417	27/64	0.434	0.5000	1/2	0.5000
1/2-20 UNF	0.446	29/64	0.457	0.5000	1/2	0.5000
9/16-12 UNC	0.472	31/64	0.490	0.5625	9/16	0.5625
9/16-18 UNF	0.502	1/2	0.515	0.5625	9/16	0.5625
5/8-11 UNC	0.527	17/32	0.546	0.6250	5/8	0.6250
5/8-18 UNF	0.565	9/16	0.578	0.6250	5/8	0.6250
3/4-10 UNC	0.642	21/32	0.663	0.7500	3/4	0.7500
3/4-16 UNF	0.682	11/16	0.696	0.7500	3/4	0.7500
7/8-9 UNC	0.755	49/64	0.778	0.8750	7/8	0.8750
7/8-14 UNF	0.798	51/64	0.814	0.8750	7/8	0.8750
1-8 UNC	0.865	7/8	0.890	1.0000	1	1.0000
1-12 UNF	0.910	59/64	0.928	1.0000	1	1.0000
1 1/8-7 UNC	0.970	63/64	0.998	1.1250	1 1/8	1.1250
1 1/8-12 UNF	1.035	1 1/32	1.053	1.1250	1 1/8	1.1250
1 1/4-7 UNC	1.095	1 7/64	1.123	1.2500	1 1/4	1.2500
1 1/4-12 UNF	1.160	1 11/64	1.178	1.2500	1 1/4	1.2500
1 3/8-6 UNC	1.195	1 13/64	1.225	1.3750	1 3/8	1.3750
1 3/8-12 UNF	1.285	1 9/32	1.303	1.3750	1 3/8	1.3750
1 1/2-6 UNC	1.320	1 11/32	1.350	1.5000	1 1/2	1.5000
1 1/2-12 UNF	1.410	1 27/64	1.428	1.5000	1 1/2	1.5000
1 3/4-5 UNC	1.534	1 9/16	1.568	1.7500	1 3/4	1.7500
2-4 1/2 UNC	1.759	1 25/32	1.795	2.0000	2	2.0000