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Screws, Threads, Taps, & Drills

Screws, Threads, Taps, & Drills

The Basics

Drill bits come in three US/English size groups and one Metric size group.

The three US/English size groups are;

Fractional sizes (such as 1/16", 1/8", 1/4", etc.)
Letter sizes (such as D, F, H, etc.)
Wire Gage or Number sizes (such as 27, 44, 10, etc.)

The Metric size group simply uses the diameter of the drill bit as a designation. (such as 1.0mm, 3.2mm, 12.7mm, etc.)

How to use these Tables

Look down the left most column to find the screw size that you will be tapping a hole for or drilling a clearance hole for. Read across in the same row to find the drill size for the material you will be drilling in. If you need a clearance hole, then read across further to find the drill size for either a close fitting hole or a loose fitting hole.

Example:
You will be using a 6-32 machine screw. Looking at the first table "US English Table", look down the left most column under "Machine Screw Size" until you come to "6". Continue across in the same horizontal row. The next column shows ".1380" which is the maximum diameter of a # 6 screw. The 3rd column "Number of Threads per Inch" indicates a choice of either 32 or 40. Choose "32" since you have a 6-32 screw. Stay in this sub-row and continue on rightward. The "Minor Diameter" is the diameter of a 6-32 from screw thread trough to screw thread trough. Now, to tap a thread, choose either "Aluminum, Brass & Plastics" for softer materials or "Stainless Steel, Steels & Iron" for harder materials depending on the material you have. If you do not need to Tap, but just drill a Clearance hole, then choose between "Close Fit" or "Free Fit". For tapping Aluminum, the drill size indicates a "36" drill. For a clearance close fit hole, the drill size indicates a "27".

Jump to the following tables

US English Table

Metric Table

Pipe Thread Table

Decimal Equivalents of all Drill Sizes Table

On small screens, scroll sideways for the following tables.

US / English Tap Drill Table
Machine Screw Size		Number of Threads Per Inch	Minor Dia.	Tap Drills				Clearance Hole Drills
				Aluminum, Brass & Plastics 75% Thread		Stainless Steel, Steels & Iron 50% Thread		All Materials
				Aluminum, Brass & Plastics 75% Thread		Stainless Steel, Steels & Iron 50% Thread		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.
0	.0600	80	.0447	3/64	.0469	55	.0520	52	.0635	50	.0700
1	.0730	64	.0538	53	.0595	1/16	.0625	48	.0760	46	.0810
1	.0730	72	.0560	53	.0595	52	.0635	48	.0760	46	.0810
2	.0860	56	.0641	50	.0700	49	.0730	43	.0890	41	.0960
2	.0860	64	.0668	50	.0700	48	.0760	43	.0890	41	.0960
3	.0990	48	.0734	47	.0785	44	.0860	37	.1040	35	.1100
3	.0990	56	.0771	45	.0820	43	.0890	37	.1040	35	.1100
4	.1120	40	.0813	43	.0890	41	.0960	32	.1160	30	.1285
4	.1120	48	.0864	42	.0935	40	.0980	32	.1160	30	.1285
5	.1250	40	.0943	38	.1015	7/64	.1094	30	.1285	29	.1360
5	.1250	44	.0971	37	.1040	35	.1100	30	.1285	29	.1360
6	.1380	32	.0997	36	.1065	32	.1160	27	.1440	25	.1495
6	.1380	40	.1073	33	.1130	31	.1200	27	.1440	25	.1495
8	.1640	32	.1257	29	.1360	27	.1440	18	.1695	16	.1770
8	.1640	36	.1299	29	.1360	26	.1470	18	.1695	16	.1770
10	.1900	24	.1389	25	.1495	20	.1610	9	.1960	7	.2010
10	.1900	32	.1517	21	.1590	18	.1695	9	.1960	7	.2010
12	.2160	24	.1649	16	.1770	12	.1890	2	.2210	1	.2280
		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
		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
		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
		24	.3239	Q	.3320	S	.3480
		32	.3367	11/32	.3438	T	.3580
7/16	.4375	14	.3499	U	.3680	25/64	.3906	29/64	.4531	15/32	.4687
		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
		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
		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
		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
3/4	.7500	10	.6273	21/32	.6562	11/16	.6875	49/64	.7656	25/32	.7812
		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
		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
		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
		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
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
		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
		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
		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

On small screens, scroll sideways for the following tables.

Metric Tap Drill Table
Tap size	Major Dia (mm)	Threads per mm	Tap Drill (mm)	Tap Drill (inch)	Clearance (mm)	Clearance (inch)
M1.6x0.35	1.6	0.35	1.25	55	1.8	49
M2x0.4	2.0	0.40	1.60	52	2.4	41
M2.5x0.45	2.5	0.45	2.05	46	2.9	32
M3x.05	3.0	0.50	2.50	39	3.4	29
M3.5x0.6	3.5	0.60	2.90	32	3.9	23
M4x0.7	4.0	0.70	3.30	30	4.5	16
M5x0.8	5.0	0.80	4.20	19	5.5	7/32
M6x1	6.0	1.00	5.0	8	6.6	G
M8x1.25	8.0	1.25	6.8	H	9.0	T
M8x1	8.0	1.00	7.0	J	9.0	T
M10x1.5	10.0	1.50	8.5	R	12.0	31/64
M10x1.25	10.0	1.25	8.8	11/32	12.0	31/64
M12x1.75	12.0	1.75	10.2	13/32	14.0	35/64
M12x1.25	12.0	1.25	10.8	27/64	14.0	35/64
M14x2	14.0	2.00	12.0	15/32	16.0	5/8
M14x1.5	14.0	1.5	12.5	1/2	16.0	5/8
M16x2	16.0	2.00	14.0	35/64	18.0	45/64
M16x1.5	16.0	1.50	14.5	37/64	18.0	45/64
M18x2.5	18.0	2.50	15.5	39/64	20.0	51/64
M18x1.5	18.0	1.50	16.5	21/32	20.0	51/64
M20x2.5	20.0	2.50	17.5	11/16	22.0	7/8
M20x1.5	20.0	1.50	18.5	47/64	22.0	7/8
M22x2.5	22.0	2.50	19.5	49/64	25.0	1
M22x1.5	22.0	1.50	20.5	13/16	25.0	1
M24x3	24.0	3.00	21.0	53/64	27.0	1-5/64
M24x2	24.0	2.00	22.0	7/8	27.0	1-5/64
M27x3	27.0	3.00	24.0	15/16	30.0	1-3/16
M27x2	27.0	2.0	25.0	1	30.0	1-3/16

On small screens, scroll sideways for the following tables.

Pipe Thread Tap Drill Table
-	American Standard			British Standard
Nominal OD	Threads per inch	NPT	NPS	Threads per inch	Drill size
1/16	27	D	1/4	28	G
1/8	27	R	S	28	11/32
1/4	18	7/16	29/64	19	15/32
3/8	18	37/64	19/32	19	39/64
1/2	14	23/32	47/64	14	3/4
5/8	-	-	-	14	53/64
3/4	14	59/64	15/16	14	31/32
7/8	-	-	-	14	1-7/64
1	11.5	1-5/32	1-3/16	11	1-7/32

On small screens, scroll sideways for the following tables.

Decimal Equivalents of Drill Sizes up to 1-1/4" (31.75mm)
Fractional Drill Sizes (inches)	Decimal Equivalent (inches)	Wire and Letter Drill Sizes	mm Drill Sizes
	.0059	97	.15
	.0063	96	.16
	.0067	95	.17
	.0071	94	.18
	.0075	93	.19
	.0079	92	.20
	.0083	91	.21
	.0087	90	.22
	.0091	89	.23
	.0094		.24
	.0095	88
	.0098		.25
	.0100	87
	.0102		.26
	.0105	86
	.0106		.27
	.0110	85	.28
	.0114		.29
	.0115	84
	.0118		.30
	.0120	83
	.0125	82
	.0126		.32
	.0130	81
	.0134		.34
	.0135	80
	.0138		.35
	.0142		.36
	.0145	79
	.0150		.38
1/64	.0156
	.0157		.40
	.0160	78
	.0165		.42
	.0173		.44
	.0177		.45
	.0180	77
	.0181		.46
	.0189		.48
	.0197		.50
	.0200	76
	.0210	75
	.0217		.55
	.0225	74
	.0236		.60
	.0240	73
	.0250	72
	.0256		.65
	.0260	71
	.0276		.70
	.0280	70
	.0292	69
	.0295		.75
	.0310	68
1/32	.0312
	.0315		.80
	.0320	67
	.0330	66
	.0335		.85
	.0350	65
	.0354		.90
	.0360	64
	.0370	63
	.0374		.95
	.0380	62
	.0390	61
	.0394		1.00
	.0400	60
	.0410	59
	.0413		1.05
	.0420	58
	.0430	57
	.0433		1.10
	.0453		1.15
	.0465	56
3/64	.0469
	.0472		1.20
	.0492		1.25
	.0512		1.30
	.0520	55
	.0531		1.35
	.0550	54
	.0551		1.40
	.0571		1.45
	.0591		1.50
	.0595	53
	.0610		1.55
1/16	.0625
	.0630		1.60
	.0635	52
	.0650		1.65
	.0669		1.70
	.0670	51
	.0689		1.75
	.0700	50
	.0709		1.80
	.0728		1.85
	.0730	49
	.0748		1.90
	.0760	48
	.0768		1.95
5/64	.0781
	.0785	47
	.0787		2.00
	.0807		2.05
	.0810	46
	.0820	45
	.0827		2.10
	.0846		2.15
	.0860	44
	.0866		2.20
	.0886		2.25
	.0890	43
	.0906		2.30
	.0925		2.35
	.0935	42
3/32	.0938
	.0945		2.40
	.0960	41
	.0965		2.45
	.0980	40
	.0984		2.50
	.0995	39
	.1015	38
	.1024		2.60
	.1040	37
	.1063		2.70
	.1065	36
	.1083		2.75
7/64	.1094
	.1100	35
	.1102		2.80
	.1110	34
	.1130	33
	.1142		2.90
	.1160	32
	.1181		3.00
	.1200	31
	.1220		3.10
1/8	.1250
	.1260		3.20
	.1280		3.25
	.1285	30
	.1299		3.30
	.1339		3.40
	.1360	29
	.1378		3.50
	.1405	28
9/64	.1406
	.1417		3.60
	.1440	27
	.1457		3.70
	.1470	26
	.1476		3.75
	.1495	25
	.1496		3.80
	.1520	24
	.1535		3.90
	.1540	23
5/32	.1562
	.1570	22
	.1575		4.00
	.1590	21
	.1610	20
	.1614		4.10
	.1654		4.20
	.1660	19
	.1673		4.25
	.1693		4.30
	.1695	18
11/64	.1719
	.1730	17
	.1732		4.40
	.1770	16
	.1772		4.50
	.1800	15
	.1811		4.60
	.1820	14
	.1850	13	4.70
	.1870		4.75
3/16	.1875
	.1890	12	4.80
	.1910	11
	.1929		4.90
	.1935	10
	.1960	9
	.1969		5.00
	.1990	8
	.2008		5.10
	.2010	7
13/64	.2031
	.2040	6
	.2047		5.20
	.2055	5
	.2067		5.25
	.2087		5.30
	.2090	4
	.2126		5.40
	.2130	3
	.2165		5.50
7/32	.2188
	.2205		5.60
	.2210	2
	.2244		5.70
	.2264		5.75
	.2280	1
	.2283		5.80
	.2323		5.90
	.2340	A
15/64	.2344
	.2362		6.00
	.2380	B
	.2402		6.10
	.2420	C
	.2441		6.20
	.2460	D
	.2461		6.25
	.2480		6.30
1/4	.2500	E	6.35
	.2520		6.40
	.2559		6.50
	.2570	F
	.2598		6.60
	.2610	G
	.2638		6.70
17/64	.2656
	.2657		6.75
	.2660	H
	.2677		6.80
	.2717		6.90
	.2720	I
	.2756		7.00
	.2770	J
	.2795		7.10
	.2810	K
9/32	.2812
	.2835		7.20
	.2854		7.25
	.2874		7.30
	.2900	L
	.2913		7.40
	.2950	M
	.2953		7.50
19/64	.2969
	.2992		7.60
	.3020	N
	.3031		7.70
	.3051		7.75
	.3071		7.80
	.3110		7.90
5/16	.3125
	.3150		8.00
	.3160	O
	.3189		8.10
	.3228		8.20
	.3230	P
	.3248		8.25
	.3268		8.30
21/64	.3281
	.3307		8.40
	.3320	Q
	.3346		8.50
	.3386		8.60
	.3390	R
	.3425		8.70
11/32	.3438
	.3445		8.75
	.3465		8.80
	.3480	S
	.3504		8.90
	.3543		9.0
	.3580	T
	.3583		9.10
23/64	.3594
	.3622		9.20
	.3642		9.25
	.3661		9.30
	.3680	U
	.3701		9.40
	.3740		9.50
3/8	.3750
	.3770	V
	.3780		9.60
	.3819		9.70
	.3839		9.75
	.3858		9.80
	.3860	W
	.3898		9.90
25/64	.3906
	.3937		10.0
	.3970	X
	.4040	Y
13/32	.4062
	.4130	Z
	.4134		10.5
27/64	.4219
	.4330		11.0
7/16	.4375
	.4528		11.5
29/64	.4531
15/32	.4668
	.4724		12.0
31/64	.4844
	.4921		12.5
1/2	.5000		12.7
	.5118		13.0
33/64	.5156
17/32	.5312
	.5315		13.5
35/64	.5469
	.5512		14.0
9/16	.5625
	.5709		14.5
37/64	.5781
	.5906		15.0
19/32	.5938
39/64	.6094
	.6102		15.5
5/8	.6250
	.6299		16.0
41/64	.6406
	.6496		16.5
21/32	.6562
	.6693		17.0
43/64	.6719
11/16	.6875
	.6890		17.5
45/64	.7031
	.7087		18.0
23/32	.7188
	.7283		18.5
47/64	.7344
	.7480		19.0
3/4	.7500		19.05
49/64	.7656
	.7677		19.5
25/32	.7812
	.7874		20.0
51/64	.7969
	.8071		20.5
13/16	.8125
	.8268		21.0
53/64	.8281
27/32	.8438
	.8465		21.5
55/64	.8594
	.8661		22.0
7/8	.8750
	.8858		22.5
57/64	.8906
	.9055		23.0
29/32	.9062
59/64	.9219
	.9252		23.5
15/16	.9375
	.9449		24.0
61/64	.9531
	.9646		24.5
31/32	.9688
	.9843		25.0
63/64	.9844
1	1.0000		25.4
	1.0039		25.5
1-1/64	1.0156
	1.0236		26.0
1-1/32	1.0312
	1.0433		26.5
1-3/64	1.0469
1-1/16	1.0625
	1.0630		27.0
1-5/64	1.0781
	1.0827		27.5
1-3/32	1.0938
	1.1024		28.0
1-7/64	1.1094
	1.1220		28.5
1-1/8	1.1250
1-9/64	1.1406
	1.1417		29.0
1-5/32	1.1562
	1.1614		29.5
1-11/64	1.1719
	1.1811		30.0
1-3/16	1.1875
	1.1910		30.25
	1.2008		30.5
1-13/64	1.2031
	1.2107		30.75
1-7/32	1.2188
	1.2205		31.0
	1.2304		31.25
1-15/64	1.2344
	1.2402		31.5
1-1/4	1.2500		31.75

Screws, Threads, Taps, & Drills

US / English Tap Drill Table

Metric Tap Drill Table

Pipe Thread Tap Drill Table

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