Standard Series Internal Unified Screw Threads Class 2
Unified Screw Thread	Tap	Min Tap Drill Size	Tap Drill	Drill	Max Tap Drill Size	Major Diameter	Clearance Drill
							Drill	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	Tap	Min Tap Drill Size	Tap Drill	Drill	Max Tap Drill Size	Major Diameter	Clearance Drill
							Drill	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