Tapping and Threading Clearance Table

Machine Screws

Tapping & Clearance Hole Information
(sizes #0 - #6)

Machine Screw Size		Number of Threads Per Inch	Minor Dia.	Tap Drills				Clearance Hole Drills				Socket Head Screw Size
				Aluminum, Brass & Plastics 75% Thread		Stainless Steel, Steels & Iron 50% Thread		All Materials
								Close Fit		Free Fit
No. or Dia.	Major Dia.			Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Head Dia.	Head Height	Hex Key
0	.0600	80	.0447	3/64	.0469	55	.0520	52	.0635	50	.0700	.096	.060	0.050
1	.0730	64	.0538	53	.0595	1/16	.0625	48	.0760	46	.0810	.118	.073	1/16
		72	.0560	53	.0595	52	.0635
2	.0860	56	.0641	50	.0700	49	.0730	43	.0890	41	.0960	.140	.086	5/64
		64	.0668	50	.0700	48	.0760
3	.0990	48	.0734	47	.0785	44	.0860	37	.1040	35	.1100	.161	.099	5/64
		56	.0771	45	.0820	43	.0890
4	.1120	40	.0813	43	.0890	41	.0960	32	.1160	30	.1285	.183	.112	3/32
		48	.0864	42	.0935	40	.0980
5	.1250	40	.0943	38	.1015	7/64	.1094	30	.1285	29	.1360	.205	.125	3/32
		44	.0971	37	.1040	35	.1100
6	.1380	32	.0997	36	.1065	32	.1160	27	.1440	25	.1495	.226	.138	7/64
		40	.1073	33	.1130	31	.1200</tbody>

(sizes #8 - 3/8)

Machine Screw Size		Number of Threads Per Inch	Minor Dia.	Tap Drills				Clearance Hole Drills				Socket Head Screw Size
				Aluminum, Brass & Plastics 75% Thread		Stainless Steel, Steels & Iron 50% Thread		All Materials
								Close Fit		Free Fit
No. or Dia.	Major Dia.			Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Head Dia.	Head Height	Hex Key
8	.1640	32	.1257	29	.1360	27	.1440	18	.1695	16	.1770	.270	.164	9/64
		36	.1299	29	.1360	26	.1470
10	.1900	24	.1389	25	.1495	20	.1610	9	.1960	7	.2010	.312	.190	5/32
		32	.1517	21	.1590	18	.1695
12	.2160	24	.1649	16	.1770	12	.1890	2	.2210	1	.2280	.324	.216	5/32
		28	.1722	14	.1820	10	.1935
		32	.1777	13	.1850	9	.1960
1/4	.2500	20	.1887	7	.2010	7/32	.2188	F	.2570	H	.2660	3/8	1/4	3/16
		28	.2062	3	.2130	1	.2280
		32	.2117	7/32	.2188	1	.2280
5/16	.3125	18	.2443	F	.2570	J	.2770	P	.3230	Q	.3320	5/32	5/16	1/4
		24	.2614	I	.2720	9/32	.2812
		32	.2742	9/32	.2812	L	.2900
3/8	.3750	16	.2983	5/16	.3125	Q	.3320	W	.3860	X	.3970	9/16	3/8	5/16
		24	.3239	Q	.3320	S	.3480
		32	.3367	11/32	.3438	T	.3580</tbody>

(sizes 7/16 - 11/16)

Machine Screw Size		Number of Threads Per Inch	Minor Dia.	Tap Drills				Clearance Hole Drills				Socket Head Screw Size
				Aluminum, Brass & Plastics 75% Thread		Stainless Steel, Steels & Iron 50% Thread		All Materials
								Close Fit		Free Fit
No. or Dia.	Major Dia.			Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Head Dia.	Head Height	Hex Key
7/16	.4375	14	.3499	U	.3680	25/64	.3906	29/64	.4531	15/32	.4687	21/32	7/16	3/8
		20	.3762	25/64	.3906	13/32	.4062
		28	.3937	Y	.4040	Z	.4130
1/2	.5000	13	.4056	27/64	.4219	29/64	.4531	33/64	.5156	17/32	.5312	3/4	1/2	3/8
		20	.4387	29/64	.4531	15/32	.4688
		28	.4562	15/32	.4688	15/32	.4688
9/16	.5625	12	.4603	31/64	.4844	33/64	.5156	37/64	.5781	19/32	.5938	27/32	9/16	7/16
		18	.4943	33/64	.5156	17/32	.5312
		24	.5114	33/64	.5156	17/32	.5312
5/8	.6250	11	.5135	17/32	.5312	9/16	.5625	41/64	.6406	21/32	.6562	15/16"	5/8	1/2
		18	.5568	37/64	.5781	19/32	.5938
		24	.5739	37/64	.5781	19/32	.5938
11/16	.6875	24	.6364	41/64	.6406	21/32	.6562	45/64	.7031	23/32	.6562			</tbody>

(sizes 3/4 - 1-3/16)

Machine Screw Size		Number of Threads Per Inch	Minor Dia.	Tap Drills				Clearance Hole Drills				Socket Head Screw Size
				Aluminum, Brass & Plastics 75% Thread		Stainless Steel, Steels & Iron 50% Thread		All Materials
								Close Fit		Free Fit
No. or Dia.	Major Dia.			Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Head Dia.	Head Height	Hex Key
3/4	.7500	10	.6273	21/32	.6562	11/16	.6875	49/64	.7656	25/32	.7812	1-1/8	3/4	5/8
		16	.6733	11/16	.6875	45/64	.7031
		20	.6887	45/64	.7031	23/32	.7188
13/16	.8125	20	.7512	49/64	.7656	25/32	.7812	53/64	.8281	27/32	.8438
7/8	.8750	9	.7387	49/64	.7656	51/64	.7969	57/64	.8906	29/32	.9062	1-5/16	7/8	3/4
		14	.7874	13/16	.8125	53/64	.8281
		20	.8137	53/64	.8281	27/32	.8438
15/16	.9375	20	.8762	57/64	.8906	29/32	.9062	61/64	.9531	31/32	.9688
1	1.000	8	.8466	7/8	.8750	59/64	.9219	1-1/64	1.0156	1-1/32	1.0313	1-1/2	1	3/4
		12	.8978	15/16	.9375	61/64	.9531
		20	.9387	61/64	.9531	31/32	.9688
1-1/16	1.0625	18	.9943	1.000	1.000	1-1/64	1.0156	1-5/64	1.0781	1-3/32	1.0938
1-1/8	1.1250	7	.9497	63/64	.9844	1-1/32	1.0313	1-9/64	1.1406	1-5/32	1.1562	1-11/16	1-1/8	7/8
		12	1.0228	1-3/64	1.0469	1-5/64	1.0781
		18	1.0568	1-1/16	1.0625	1-5/64	1.0781
1-3/16	1.1875	18	1.1193	1-1/8	1.1250	1-9/64	1.1406	1-13/64	1.2031	1-7/32	1.2188			</tbody>

(sizes 1-1/4 - 1-3/4)

Machine Screw Size		Number of Threads Per Inch	Minor Dia.	Tap Drills				Clearance Hole Drills				Socket Head Screw Size
				Aluminum, Brass & Plastics 75% Thread		Stainless Steel, Steels & Iron 50% Thread		All Materials
								Close Fit		Free Fit
No. or Dia.	Major Dia.			Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Drill Size	Decimal Equiv.	Head Dia.	Head Height	Hex Key
1-1/4	1.2500	7	1.0747	1-7/64	1.1094	1-5/32	1.1562	1-17/64	1.2656	1-9/32	1.2812	1 7/8	1-1/4	7/8
		12	1.1478	1-11/64	1.1719	1-13/64	1.2031
		18	1.1818	1-3/16	1.1875	1-13/64	1.2031
1-5/16	1.3125	18	1.2443	1-1/4	1.2500	1-17/64	1.2656	1-21/64	1.3281	1-11/32	1.3438
1-3/8	1.3750	6	1.1705	1-7/32	1.2187	1-17/64	1.2656	1-25/64	1.3906	1-13/32	1.4062	2 1/16	1-3/8	1
		12	1.2728	1-19/64	1.2969	1-21/64	1.3281
		18	1.3068	1-5/16	1.3125	1-21/64	1.3281
1-7/16	1.4375	18	1.3693	1-3/8	1.3750	1-25/64	1.3906	1-29/64	1.4531	1-15/32	1.4688
1-1/2	1.500	6	1.2955	1-11/32	1.3437	1-25/64	1.3906	1-33/64	1.5156	1-17/32	1.5312	2 1/4	1-1/2	1
		12	1.3978	1-27/64	1.4219	1-7/16	1.4375
		18	1.4318	1-7/16	1.4375	1-29/64	1.4531
1-9/16	1.5625	18	1.4943	1-12	1.500	1-33/64	1.5156	1-37/64	1.5781	1-19/32	1.5938
1-5/8	1.625	18	1.5568	1-9/16	1.5625	1-37/64	1.5781	1-41/64	1.6406	1-21/32	1.6562
1-11/16	1.6875	18	1.6193	1-5/8	1.6250	1-41/64	1.6406	1-45/64	1.7031	1-23/32	1.7188
1-3/4	1.750	5	1.5046	1-9/16	1.5625	1-5/8	1.6250	1-49/64	1.7659	1-25/32	1.7812	2 5/8	1-3/4	1-1/4 </tbody>

This chart obtained from Marcus Hertlein who apparently got it from Dominik Hoffmann (see below). Converted to wiki by HTML to Wiki Converter - tables

Modified version, originally by dhoffmann@cfaNOSPAM.harvard.edu Dominik Hoffmann © 1996