Tap & Drill Chart

UNC - UNIFIED NATIONAL COARSE

Size - Imperial	Threads Per Inch	TAPPING DRILL SIZE
		Preferred		Alternative
		mm	inch	mm	inch
#1	64	1.50	53	1.55
#2	56	1.85	50	1.80
#3	48	2.10	47	2.05	5/64
#4	40	2.35	3/32	2.30	43
#5	40	2.65	38	2.60
#6	32	2.85	36	2.80	7/64
#8	32	3.50	29	3.40
#10	24	3.90	25	3.00	5/32
#12	24	4.50	16	4.40	11/64
1/4	20	5.20	13/64	5.10	7
5/16	18	6.60	17/64	6.50	F
3/8	16	8.10	5/16	8.00
7/16	14	9.50	3/8	9.40	23/64
1/2	13	11.00	27/64	10.80
9/16	12	12.20	31/64
5/8	11	13.80	35/64	13.50	17/32
3/4	10		21/32	16.50	41/64
7/8	9	19.50	49/64
1	8		7/8	22.50
1-1/8	7		63/64	25.00
1-1/4	7		1-7/6	28.00
1-3/8	6	31.00	1-7/32	30.75	1-13/64
1-1/2	6		1-11/32	34.00	1-21/64
1-3/4	5		1-9/16	39.50
2	4-1/2		1-25/32	45.00

UNF - UNIFIED NATIONAL FINE

Size - Imperial	Threads Per Inch	TAPPING DRILL SIZE
		Preferred		Alternative
		mm	inch	mm	inch
#0	80	1.25	3/64
#1	72	1.55	53
#2	64	1.90	50
#3	56	2.15	45
#4	48	2.40	42		3/32
#5	44	2.70	37	2.65
#6	40	2.95	33	2.90
#8	36	3.60	9/64	3.50	29
#10	32	4.10	21	4.00	5/32
#12	28	4.70	14	4.60
1/4	28	5.50	7/32	5.40	3
5/16	24	6.90	17/64	6.80	1
3/8	24	8.50	Q	8.40	21/64
7/16	20	10.00	25/64	9.80
1/2	20	11.50	29/64
9/16	18	12.90	33/64	12.80
5/8	18	14.50	37/64
3/4	16	17.50	11/16
7/8	14	20.40	13/16	20.50
1	12	23.25	59/64	23.50
1	14*	23.50	15/16
1-1/8	12	26.50	1-3/64
1-1/4	12	29.50	1-11/64
1-3/8	12	33.00	1-19/64
1-1/2	12	36.00	1-27/64

*1-12 Thread is UNF
standard, however 1-14
is popular demand and
generally stocked in
place of 1-12.

METRIC COARSE

Size - MM	Pitch	TAPPING DRILL SIZE
		Preferred		Alternative
		mm	inch	mm	inch
1.6	0.35	1.25	3/64
1.7	0.35	1.35	55
1.8	0.35	1.45	54
2	0.40	1.60	1/16
2.5	0.45	2.05	46
3	0.50	2.50	40
3.5	0.60	2.90	33
4	0.70	3.30	30
4.5	0.75	3.70	27
5	0.80	4.30	11/64	4.20	19
6	1.00	5.10	13/64	5.00	9
7	1.00	6.10		6.00	15/64
8	1.25	6.90	H	6.80	17/64
9	1.25	7.90	5/16	7.80
10	1.50	8.60	11/32	8.50	Q
11	1.50	9.50	3/8
12	1.75		13/32	10.20	Y
14	2.00	12.20	31/64	12.00	15/32
16	2.00	14.25	9/16	14.00	35/64
18	2.50	15.75		15.50	39/64
20	2.50		45/64	17.50	11/16
22	2.50		23/32	19.50	49/64
24	3.00	21.00	53/64
27	3.00	24.00	61/64		15/16
30	3.50	26.50	1-3/64
33	3.50		1-11/64		1-5/32
36	4.00		1-17/64	29.50	1-1/4
39	4.00	35.00	1-3/8	32.00

METRIC FINE

Size - MM	Pitch	TAPPING DRILL SIZE
		Preferred		Alternative
		mm	inch	mm	inch
4	0.50	3.50	29		9/64
5	0.50	4.50	16
6	0.75	5.25	5
7	0.75	6.25	D	6.20	1/4
8	1.00	7.00	J	7.10	9/32
10	1.25	8.75	11/32		S
10	1.00	9.00	T		23/64
12	1.50	10.50	27/64		Z
12	1.25	27/64
12	1.00	11.00	7/16
14	1.50	12.50	31/64		1/2
16	1.50	14.75	37/64	14.50	9/16
18	2.00	16.00	5/8
18	1.50	16.50	21/32	16.50
20	2.00	18.00	45/64
20	1.50	18.50	47/64
22	2.00	20.00	25/32
22	1.50	20.50	13/16	20.50
24	2.00	22.00	7/8
24	1.50	22.50	7/8

BSW - BRITISH STANDARD WHITWORTH

Size - Imperial	Threads Per Inch	TAPPING DRILL SIZE
		Preferred		Alternative
		mm	inch	mm	inch
1/16*	60	1.20	3/64	1.05
3/32*	48	1.90	49	1.75
1/8	40	2.55		2.50	3/32
5/32*	32	3.20	1/8	2.95
3/16	24	3.70		3.60	9/64
7/32*	24	4.50		4.30	11/64
1/4	20	5.10		5.00	3/16
5/16	18	6.50		6.40	1/4
3/8	16	7.90	5/16	7.80	19/64
7/16	14	9.50		9.20	23/64
1/2	12	10.50			13/32
9/16	12			12.00	15/32
5/8	11	13.50	17/32		33/64
3/4	10	16.50	41/64	16.00	5/8
7/8	9		3/4	19.00	47/64
1	8	22.00	55/64		27/32
1-1/8	7		31/32	24.50	61/64
1-1/4	7	28.00	1-3/32	27.50	1-5/64
1-1/2	6	33.50	1-5/16	33.00	1-19/64
1-3/4	5	39.00	1-17/32	38.50	1-33/64
2	1-1/2	44.50	1-49/64	44.00	1-3/4

BSF - BRITISH STANDARD FINE

Size - Imperial	Threads Per Inch	TAPPING DRILL SIZE
		Preferred		Alternative
		mm	inch	mm	inch
3/16	32	4.00	5/32	3.90
1/4	26	5.30		5.20	13/64
5/16	22	6.80	17/64	6.70
3/8	20	8.30	21/64	8.20	5/16
7/16	18			9.50	3/8
1/2	16		7/16	11.00	27/64
9/16	16		1/2	12.50	31/64
5/8	14	14.00	35/64	13.80	17/32
3/4	12			16.50	21/32
7/8	11		25/32	19.50	49/64
1	10		57/64	22.50	7/8
1-1/4	9	28.50	1-1/8		1-7/64
1-1/2	8	34.50	1-23/64		1-11/32
1-3/4	7	40.50	1-19/32	40.00	1-37/64

NPT - NATIONAL PIPE TAPER

Size - Imperial	Threads Per Inch	TAPPING DRILL SIZE
		Preferred		Alternative
		mm	inch	mm	inch
1/16	27		D	6.30	1/4
1/8	27		R	8.70	11/32
1/4	18		7/16	11.10
3/8	18		9/16	14.50	37/64
1/2	14		23/32	18.00
3/4	14		59/64	23.25	15/16
1	11-1/2		1-5/32	29.00
1-1/4	11-1/2		1-1/2	38.00
1-1/2	11-1/2		1-47/64	44.00
2	11-1/2		2-7/32	56.00
2-1/2	8		2-5/8	67.00
3	8		3-1/4	82.50

DRILL SIZE	DEC EQUIV.	MM	DRILL SIZE	DEC EQUIV.	MM	DRILL SIZE	DEC EQUIV.	MM	DRILL SIZE	DEC EQUIV.	MM
-	.0039	0.10	45	.0820	2.08	4	.2090	5.31	15/32	.4688	11.91
-	.0079	0.20	44	.0860	2.18	3	.2130	5.41	-	.4724	12.00
-	.0098	0.25	43	.0890	2.26	7/32	.2188	5.56	31/64	.4844	12.30
-	.0118	0.30	42	.0935	2.37	2	.2210	6.61	1/2	.5000	12.70
80	.0135	0.34	3/32	.0938	2.38	1	.2280	5.79	-	.5118	13.00
79	.0145	0.37	41	.0960	2.44	A	.2340	5.94	33/64	.5156	13.10
1/64	.0156	0.40	40	.0980	2.50	15/64	.2344	5.95	17/32	.5312	13.49
78	.0160	0.41	39	.0995	2.53	-	.2362	6.00	35/64	.5469	13.89
77	.0181	0.46	38	.1015	2.58	B	.2380	6.05	-	.5512	14.00
-	.0197	0.50	37	.1040	2.64	C	.2420	6.15	9/16	.5625	1429
76	.0200	0.51	36	.1065	2.71	D	.2460	6.25	37/64	.5781	14.68
75	.0210	0.53	7/64	.1094	2.78	1/4	.2500	6.35	-	.5906	15.00
74	.0225	0.57	35	.1100	2.79	E	.2500	6.35	19/32	.5938	15.08
-	.0236	0.60	34	.1110	2.79	F	.2570	6.53	39/64	.6094	15.48
73	.0240	0.61	33	.1130	2.87	G	.2610	6.63	5/8	.6250	15.88
72	.0250	0.64	32	.1160	2.95	17/64	.2656	6.75	-	.6299	16.00
71	.0260	0.66	-	.1181	3.00	H	.2660	6.76	41/64	.6406	16.27
-	.0276	0.70	31	.1200	3.05	I	.2720	6.91	21/32	.6562	16.67
70	.0280	0.71	1/8	.1250	3.18	-	.2756	7.00	-	.6693	17.00
69	.0292	0.74	30	.1285	3.26	J	.2770	7.04	43/64	.6719	17.07
-	.0295	0.75	29	.1360	3.45	K	.2810	7.14	11/16	.6875	17.46
68	.0310	0.79	28	.1405	3.57	9/32	.2812	7.14	45/64	.7031	17.88
1/32	.0313	0.79	9/64	.1406	3.57	L	.2900	7.37	-	.7087	18.00
-	.0315	0.80	27	.1440	3.66	M	.2950	7.49	23/32	.7188	18.26
67	.0320	0.81	26	.1470	3.73	19/64	.2969	7.54	47/64	.7344	18.65
66	.0330	0.84	25	.1495	3.80	N	.3020	7.67	-	.7344	18.65
65	.0350	0.89	24	.1520	3.86	5/16	.3125	7.94	3/4	.7500	19.05
-	.0354	0.90	23	.1540	3.91	-	.3150	8.00	49/64	.7656	19.45
64	.0360	0.91	5/32	.1562	3.97	O	.3160	8.03	25/32	.7812	19.84
63	.0370	0.94	22	.1570	3.99	P	.3230	8.20	-	.7874	20.00
62	.0380	0.97	-	.1575	4.00	21/64	.3281	8.33	51/64	.7969	20.24
61	.0394	0.99	21	.1590	4.04	Q	.2230	8.43	13/16	.8125	20.64
-	.0394	1.00	20	.1610	4.09	R	.3390	8.61	-	.8268	21.00
60	.0400	1.02	19	.1660	4.22	11/32	.3438	8.73	53/64	.8281	21.03
59	.0410	1.04	18	.1695	4.31	S	.3480	8.84	27/32	.8438	21.43
58	.0420	1.07	11/64	.1719	4.37	-	.3543	9.00	55/64	.8594	21.84
57	.0430	1.09	17	.1730	4.39	T	.3580	9.09	-	.8661	22.00
56	.0465	1.18	16	.1770	4.50	23/64	.3594	9.13	7/8	.8750	22.23
3/64	.0469	1.19	15	.1800	4.57	U	.3680	9.35	57/64	.8906	22.62
55	.0520	1.32	14	.1820	4.62	3/8	.3750	9.35	-	.9055	23.00
54	.0550	1.40	13	.1850	4.70	V	.3770	9.56	29/32	.9062	23.02
53	.0595	1.51	3/16	.1875	4.76	W	.3860	9.80	59/64	.9219	23.42
1/16	.0625	1.59	12	.1890	4.80	25/64	.3906	9.92	15/16	.9375	23.81
52	.0635	1.61	11	.1910	4.85	-	.3937	10.00	-	.9449	24.00
51	.0670	1.70	10	.1935	4.91	X	.3970	10.08	61/64	.9531	24.21
50	.0700	1.78	9	.1960	4.98	Y	.4040	10.26	31/32	.9688	24.61
49	.0730	1.85	-	.1968	5.00	13/32	.4062	10.32	-	.9842	25.00
48	.0760	1.93	8	.1990	5.05	Z	.4130	10.49	63/64	.9844	25.00
5/64	.0781	1.98	7	.2010	5.11	27/64	.4219	10.72	1	1.00	25.40
47	.0785	1.99	13/64	.2031	5.16	-	.4331	11.00
-	.0787	2.00	6	.2040	5.18	7/16	.4375	11.11
46	.0810	1.06	5	.2055	5.22	29/64	.4531	11.51

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