Drilling

Drill Bit Size Chart

Fractional, number, letter and metric bits interleaved by actual diameter — the way they sit in a drill index, not split into four separate tables you have to cross-check.

The four systems overlap heavily. 1/4″, E and 6.35 mm are the same hole. A #7 (0.2010″) and a 5.1 mm (0.2008″) differ by two ten-thousandths — interchangeable for clearance, not for a reamed fit.

Fractional, number, letter and metric drill bit sizes sorted by diameter, with interchangeable sizes
			Interchangeable with
#80	Number	0.0135 in / mm	#79
#79	Number	0.0145 in / mm	#80, 1/64", #78
1/64"	Fractional	0.0156 in / mm	#79, #78
#78	Number	0.0160 in / mm	1/64", #79, #77
#77	Number	0.0180 in / mm	#78, 0.5 mm
0.5 mm	Metric	0.0197 in / mm	#77, #76, #75
#76	Number	0.0200 in / mm	0.5 mm, #75
#75	Number	0.0210 in / mm	#76, 0.5 mm, #74
#74	Number	0.0225 in / mm	#75, 0.6 mm, #73
0.6 mm	Metric	0.0236 in / mm	#74, #73, #72
#73	Number	0.0240 in / mm	0.6 mm, #74, #72, #71
#72	Number	0.0250 in / mm	#73, 0.6 mm, #71
#71	Number	0.0260 in / mm	#72, #73, 0.7 mm
0.7 mm	Metric	0.0276 in / mm	#71, #70, #69
#70	Number	0.0280 in / mm	0.7 mm, #69
#69	Number	0.0292 in / mm	#70, 0.7 mm, #68
#68	Number	0.0310 in / mm	#69, 1/32", 0.8 mm, #67
1/32"	Fractional	0.0312 in / mm	#68, 0.8 mm, #67, #66
0.8 mm	Metric	0.0315 in / mm	1/32", #68, #67, #66
#67	Number	0.0320 in / mm	0.8 mm, 1/32", #68, #66
#66	Number	0.0330 in / mm	#67, 0.8 mm, 1/32"
#65	Number	0.0350 in / mm	0.9 mm, #64, #63
0.9 mm	Metric	0.0354 in / mm	#65, #64, #63
#64	Number	0.0360 in / mm	0.9 mm, #65, #63
#63	Number	0.0370 in / mm	#64, 0.9 mm, #65, #62
#62	Number	0.0380 in / mm	#63, #61, 1.0 mm
#61	Number	0.0390 in / mm	#62, 1.0 mm, #60
1.0 mm	Metric	0.0394 in / mm	#61, #62, #60, #59
#60	Number	0.0400 in / mm	1.0 mm, #61, #59
#59	Number	0.0410 in / mm	#60, 1.0 mm, #58, #57
#58	Number	0.0420 in / mm	#59, #57, 1.1 mm
#57	Number	0.0430 in / mm	#58, #59, 1.1 mm
1.1 mm	Metric	0.0433 in / mm	#57, #58
#56	Number	0.0465 in / mm	3/64", 1.2 mm
3/64"	Fractional	0.0469 in / mm	#56, 1.2 mm
1.2 mm	Metric	0.0472 in / mm	3/64", #56
1.3 mm	Metric	0.0512 in / mm	#55
#55	Number	0.0520 in / mm	1.3 mm
#54	Number	0.0550 in / mm	1.4 mm
1.4 mm	Metric	0.0551 in / mm	#54
1.5 mm	Metric	0.0591 in / mm	#53
#53	Number	0.0595 in / mm	1.5 mm
1/16"	Fractional	0.0625 in / mm	1.6 mm, #52
1.6 mm	Metric	0.0630 in / mm	1/16", #52
#52	Number	0.0635 in / mm	1.6 mm, 1/16"
1.7 mm	Metric	0.0669 in / mm	#51
#51	Number	0.0670 in / mm	1.7 mm
#50	Number	0.0700 in / mm	1.8 mm
1.8 mm	Metric	0.0709 in / mm	#50
#49	Number	0.0730 in / mm	1.9 mm
1.9 mm	Metric	0.0748 in / mm	#49, #48
#48	Number	0.0760 in / mm	1.9 mm
5/64"	Fractional	0.0781 in / mm	#47, 2.0 mm
#47	Number	0.0785 in / mm	5/64", 2.0 mm
2.0 mm	Metric	0.0787 in / mm	#47, 5/64"
#46	Number	0.0810 in / mm	#45, 2.1 mm
#45	Number	0.0820 in / mm	#46, 2.1 mm
2.1 mm	Metric	0.0827 in / mm	#45, #46
#44	Number	0.0860 in / mm	2.2 mm
2.2 mm	Metric	0.0866 in / mm	#44
#43	Number	0.0890 in / mm	2.3 mm
2.3 mm	Metric	0.0906 in / mm	#43
#42	Number	0.0935 in / mm	3/32", 2.4 mm
3/32"	Fractional	0.0938 in / mm	#42, 2.4 mm
2.4 mm	Metric	0.0945 in / mm	3/32", #42, #41
#41	Number	0.0960 in / mm	2.4 mm
#40	Number	0.0980 in / mm	2.5 mm, #39
2.5 mm	Metric	0.0984 in / mm	#40, #39
#39	Number	0.0995 in / mm	2.5 mm, #40
#38	Number	0.1015 in / mm	2.6 mm
2.6 mm	Metric	0.1024 in / mm	#38, #37
#37	Number	0.1040 in / mm	2.6 mm
2.7 mm	Metric	0.1063 in / mm	#36
#36	Number	0.1065 in / mm	2.7 mm
7/64"	Fractional	0.1094 in / mm	#35, 2.8 mm, #34
#35	Number	0.1100 in / mm	7/64", 2.8 mm, #34
2.8 mm	Metric	0.1102 in / mm	#35, 7/64", #34
#34	Number	0.1110 in / mm	2.8 mm, #35, 7/64"
#33	Number	0.1130 in / mm	2.9 mm
2.9 mm	Metric	0.1142 in / mm	#33, #32
#32	Number	0.1160 in / mm	2.9 mm
3.0 mm	Metric	0.1181 in / mm	#31
#31	Number	0.1200 in / mm	3.0 mm
3.1 mm	Metric	0.1221 in / mm
1/8"	Fractional	0.1250 in / mm	3.2 mm
3.2 mm	Metric	0.1260 in / mm	1/8"
#30	Number	0.1285 in / mm	3.3 mm
3.3 mm	Metric	0.1299 in / mm	#30
3.4 mm	Metric	0.1339 in / mm
#29	Number	0.1360 in / mm	3.5 mm
3.5 mm	Metric	0.1378 in / mm	#29
#28	Number	0.1405 in / mm	9/64", 3.6 mm
9/64"	Fractional	0.1406 in / mm	#28, 3.6 mm
3.6 mm	Metric	0.1417 in / mm	9/64", #28
#27	Number	0.1440 in / mm	3.7 mm
3.7 mm	Metric	0.1457 in / mm	#27, #26
#26	Number	0.1470 in / mm	3.7 mm
#25	Number	0.1495 in / mm	3.8 mm
3.8 mm	Metric	0.1496 in / mm	#25
#24	Number	0.1520 in / mm	3.9 mm
3.9 mm	Metric	0.1535 in / mm	#24, #23
#23	Number	0.1540 in / mm	3.9 mm
5/32"	Fractional	0.1562 in / mm	#22, 4.0 mm
#22	Number	0.1570 in / mm	5/32", 4.0 mm
4.0 mm	Metric	0.1575 in / mm	#22, 5/32", #21
#21	Number	0.1590 in / mm	4.0 mm
#20	Number	0.1610 in / mm	4.1 mm
4.1 mm	Metric	0.1614 in / mm	#20
4.2 mm	Metric	0.1653 in / mm	#19
#19	Number	0.1660 in / mm	4.2 mm
4.3 mm	Metric	0.1693 in / mm	#18
#18	Number	0.1695 in / mm	4.3 mm
11/64"	Fractional	0.1719 in / mm	#17, 4.4 mm
#17	Number	0.1730 in / mm	11/64", 4.4 mm
4.4 mm	Metric	0.1732 in / mm	#17, 11/64"
#16	Number	0.1770 in / mm	4.5 mm
4.5 mm	Metric	0.1772 in / mm	#16
#15	Number	0.1800 in / mm	4.6 mm
4.6 mm	Metric	0.1811 in / mm	#15, #14
#14	Number	0.1820 in / mm	4.6 mm
#13	Number	0.1850 in / mm	4.7 mm
4.7 mm	Metric	0.1850 in / mm	#13
3/16"	Fractional	0.1875 in / mm	4.8 mm, #12
4.8 mm	Metric	0.1890 in / mm	3/16", #12
#12	Number	0.1890 in / mm	4.8 mm, 3/16"
#11	Number	0.1910 in / mm	4.9 mm
4.9 mm	Metric	0.1929 in / mm	#11, #10
#10	Number	0.1935 in / mm	4.9 mm
#9	Number	0.1960 in / mm	5.0 mm
5.0 mm	Metric	0.1968 in / mm	#9
#8	Number	0.1990 in / mm	5.1 mm
5.1 mm	Metric	0.2008 in / mm	#8, #7
#7	Number	0.2010 in / mm	5.1 mm
13/64"	Fractional	0.2031 in / mm	#6, 5.2 mm
#6	Number	0.2040 in / mm	13/64", 5.2 mm, #5
5.2 mm	Metric	0.2047 in / mm	#6, 13/64", #5
#5	Number	0.2055 in / mm	5.2 mm, #6
5.3 mm	Metric	0.2087 in / mm	#4
#4	Number	0.2090 in / mm	5.3 mm
5.4 mm	Metric	0.2126 in / mm	#3
#3	Number	0.2130 in / mm	5.4 mm
5.5 mm	Metric	0.2165 in / mm
7/32"	Fractional	0.2188 in / mm	5.6 mm
5.6 mm	Metric	0.2205 in / mm	7/32", #2
#2	Number	0.2210 in / mm	5.6 mm
5.7 mm	Metric	0.2244 in / mm
#1	Number	0.2280 in / mm	5.8 mm
5.8 mm	Metric	0.2283 in / mm	#1
5.9 mm	Metric	0.2323 in / mm	A
A	Letter	0.2340 in / mm	5.9 mm, 15/64"
15/64"	Fractional	0.2344 in / mm	A, 6.0 mm
6.0 mm	Metric	0.2362 in / mm	15/64", B
B	Letter	0.2380 in / mm	6.0 mm
6.1 mm	Metric	0.2402 in / mm	C
C	Letter	0.2420 in / mm	6.1 mm
6.2 mm	Metric	0.2441 in / mm	D
D	Letter	0.2460 in / mm	6.2 mm
6.3 mm	Metric	0.2480 in / mm	1/4", E
1/4"	Fractional	0.2500 in / mm	6.3 mm, E, 6.4 mm
E	Letter	0.2500 in / mm	1/4", 6.3 mm, 6.4 mm
6.4 mm	Metric	0.2520 in / mm	E, 1/4"
6.5 mm	Metric	0.2559 in / mm	F
F	Letter	0.2570 in / mm	6.5 mm
6.6 mm	Metric	0.2598 in / mm	G
G	Letter	0.2610 in / mm	6.6 mm
6.7 mm	Metric	0.2638 in / mm	17/64"
17/64"	Fractional	0.2656 in / mm	6.7 mm, H
H	Letter	0.2660 in / mm	17/64", 6.8 mm
6.8 mm	Metric	0.2677 in / mm	H
6.9 mm	Metric	0.2717 in / mm	I
I	Letter	0.2720 in / mm	6.9 mm
7.0 mm	Metric	0.2756 in / mm	J
J	Letter	0.2770 in / mm	7.0 mm
7.1 mm	Metric	0.2795 in / mm	K, 9/32"
K	Letter	0.2810 in / mm	7.1 mm, 9/32"
9/32"	Fractional	0.2812 in / mm	K, 7.1 mm
7.2 mm	Metric	0.2835 in / mm
7.3 mm	Metric	0.2874 in / mm
L	Letter	0.2900 in / mm	7.4 mm
7.4 mm	Metric	0.2913 in / mm	L
M	Letter	0.2950 in / mm	7.5 mm, 19/64"
7.5 mm	Metric	0.2953 in / mm	M, 19/64"
19/64"	Fractional	0.2969 in / mm	7.5 mm, M
7.6 mm	Metric	0.2992 in / mm
N	Letter	0.3020 in / mm	7.7 mm
7.7 mm	Metric	0.3031 in / mm	N
7.8 mm	Metric	0.3071 in / mm
7.9 mm	Metric	0.3110 in / mm	5/16"
5/16"	Fractional	0.3125 in / mm	7.9 mm
8.0 mm	Metric	0.3150 in / mm	O
O	Letter	0.3160 in / mm	8.0 mm
8.1 mm	Metric	0.3189 in / mm
8.2 mm	Metric	0.3228 in / mm	P
P	Letter	0.3230 in / mm	8.2 mm
8.3 mm	Metric	0.3268 in / mm	21/64"
21/64"	Fractional	0.3281 in / mm	8.3 mm
8.4 mm	Metric	0.3307 in / mm	Q
Q	Letter	0.3320 in / mm	8.4 mm
8.5 mm	Metric	0.3347 in / mm
8.6 mm	Metric	0.3386 in / mm	R
R	Letter	0.3390 in / mm	8.6 mm
8.7 mm	Metric	0.3425 in / mm	11/32"
11/32"	Fractional	0.3438 in / mm	8.7 mm
8.8 mm	Metric	0.3465 in / mm	S
S	Letter	0.3480 in / mm	8.8 mm
8.9 mm	Metric	0.3504 in / mm
9.0 mm	Metric	0.3543 in / mm
T	Letter	0.3580 in / mm	9.1 mm, 23/64"
9.1 mm	Metric	0.3583 in / mm	T, 23/64"
23/64"	Fractional	0.3594 in / mm	9.1 mm, T
9.2 mm	Metric	0.3622 in / mm
9.3 mm	Metric	0.3661 in / mm	U
U	Letter	0.3680 in / mm	9.3 mm
9.4 mm	Metric	0.3701 in / mm
9.5 mm	Metric	0.3740 in / mm	3/8"
3/8"	Fractional	0.3750 in / mm	9.5 mm
V	Letter	0.3770 in / mm	9.6 mm
9.6 mm	Metric	0.3780 in / mm	V
9.7 mm	Metric	0.3819 in / mm
9.8 mm	Metric	0.3858 in / mm	W
W	Letter	0.3860 in / mm	9.8 mm
9.9 mm	Metric	0.3898 in / mm	25/64"
25/64"	Fractional	0.3906 in / mm	9.9 mm
10.0 mm	Metric	0.3937 in / mm
X	Letter	0.3970 in / mm	10.1 mm
10.1 mm	Metric	0.3976 in / mm	X
10.2 mm	Metric	0.4016 in / mm
Y	Letter	0.4040 in / mm	10.3 mm
10.3 mm	Metric	0.4055 in / mm	Y, 13/32"
13/32"	Fractional	0.4062 in / mm	10.3 mm
10.4 mm	Metric	0.4094 in / mm
Z	Letter	0.4130 in / mm	10.5 mm
10.5 mm	Metric	0.4134 in / mm	Z
10.6 mm	Metric	0.4173 in / mm
10.7 mm	Metric	0.4213 in / mm	27/64"
27/64"	Fractional	0.4219 in / mm	10.7 mm
10.8 mm	Metric	0.4252 in / mm
10.9 mm	Metric	0.4291 in / mm
11.0 mm	Metric	0.4331 in / mm
11.1 mm	Metric	0.4370 in / mm	7/16"
7/16"	Fractional	0.4375 in / mm	11.1 mm
11.2 mm	Metric	0.4409 in / mm
11.3 mm	Metric	0.4449 in / mm
11.4 mm	Metric	0.4488 in / mm
11.5 mm	Metric	0.4528 in / mm	29/64"
29/64"	Fractional	0.4531 in / mm	11.5 mm
11.6 mm	Metric	0.4567 in / mm
11.7 mm	Metric	0.4606 in / mm
11.8 mm	Metric	0.4646 in / mm
11.9 mm	Metric	0.4685 in / mm	15/32"
15/32"	Fractional	0.4688 in / mm	11.9 mm
12.0 mm	Metric	0.4724 in / mm
12.1 mm	Metric	0.4764 in / mm
12.2 mm	Metric	0.4803 in / mm
12.3 mm	Metric	0.4843 in / mm	31/64"
31/64"	Fractional	0.4844 in / mm	12.3 mm
12.4 mm	Metric	0.4882 in / mm
12.5 mm	Metric	0.4921 in / mm
12.6 mm	Metric	0.4961 in / mm
1/2"	Fractional	0.5000 in / mm	12.7 mm
12.7 mm	Metric	0.5000 in / mm	1/2"
12.8 mm	Metric	0.5039 in / mm
12.9 mm	Metric	0.5079 in / mm
13.0 mm	Metric	0.5118 in / mm
33/64"	Fractional	0.5156 in / mm
17/32"	Fractional	0.5312 in / mm	13.5 mm
13.5 mm	Metric	0.5315 in / mm	17/32"
35/64"	Fractional	0.5469 in / mm
14.0 mm	Metric	0.5512 in / mm
9/16"	Fractional	0.5625 in / mm
14.5 mm	Metric	0.5709 in / mm
37/64"	Fractional	0.5781 in / mm
15.0 mm	Metric	0.5906 in / mm
19/32"	Fractional	0.5938 in / mm
39/64"	Fractional	0.6094 in / mm	15.5 mm
15.5 mm	Metric	0.6102 in / mm	39/64"
5/8"	Fractional	0.6250 in / mm
16.0 mm	Metric	0.6299 in / mm
41/64"	Fractional	0.6406 in / mm
16.5 mm	Metric	0.6496 in / mm
21/32"	Fractional	0.6562 in / mm
17.0 mm	Metric	0.6693 in / mm
43/64"	Fractional	0.6719 in / mm
11/16"	Fractional	0.6875 in / mm	17.5 mm
17.5 mm	Metric	0.6890 in / mm	11/16"
45/64"	Fractional	0.7031 in / mm
18.0 mm	Metric	0.7087 in / mm
23/32"	Fractional	0.7188 in / mm
18.5 mm	Metric	0.7284 in / mm
47/64"	Fractional	0.7344 in / mm
19.0 mm	Metric	0.7480 in / mm	3/4"
3/4"	Fractional	0.7500 in / mm	19.0 mm
49/64"	Fractional	0.7656 in / mm
19.5 mm	Metric	0.7677 in / mm
25/32"	Fractional	0.7812 in / mm
20.0 mm	Metric	0.7874 in / mm
51/64"	Fractional	0.7969 in / mm
20.5 mm	Metric	0.8071 in / mm
13/16"	Fractional	0.8125 in / mm
21.0 mm	Metric	0.8268 in / mm	53/64"
53/64"	Fractional	0.8281 in / mm	21.0 mm
27/32"	Fractional	0.8438 in / mm
21.5 mm	Metric	0.8465 in / mm
55/64"	Fractional	0.8594 in / mm
22.0 mm	Metric	0.8661 in / mm
7/8"	Fractional	0.8750 in / mm
22.5 mm	Metric	0.8858 in / mm
57/64"	Fractional	0.8906 in / mm
23.0 mm	Metric	0.9055 in / mm	29/32"
29/32"	Fractional	0.9062 in / mm	23.0 mm
59/64"	Fractional	0.9219 in / mm
23.5 mm	Metric	0.9252 in / mm
15/16"	Fractional	0.9375 in / mm
24.0 mm	Metric	0.9449 in / mm
61/64"	Fractional	0.9531 in / mm
24.5 mm	Metric	0.9646 in / mm
31/32"	Fractional	0.9688 in / mm
25.0 mm	Metric	0.9842 in / mm	63/64"
63/64"	Fractional	0.9844 in / mm	25.0 mm
1"	Fractional	1.0000 in / mm
1-1/32"	Fractional	1.0312 in / mm
1-1/16"	Fractional	1.0625 in / mm
1-3/32"	Fractional	1.0938 in / mm
1-1/8"	Fractional	1.1250 in / mm
1-5/32"	Fractional	1.1562 in / mm
1-3/16"	Fractional	1.1875 in / mm
1-7/32"	Fractional	1.2188 in / mm
1-1/4"	Fractional	1.2500 in / mm
1-9/32"	Fractional	1.2812 in / mm
1-5/16"	Fractional	1.3125 in / mm
1-11/32"	Fractional	1.3438 in / mm
1-3/8"	Fractional	1.3750 in / mm
1-13/32"	Fractional	1.4062 in / mm
1-7/16"	Fractional	1.4375 in / mm
1-15/32"	Fractional	1.4688 in / mm
1-1/2"	Fractional	1.5000 in / mm
1-17/32"	Fractional	1.5312 in / mm
1-9/16"	Fractional	1.5625 in / mm
1-19/32"	Fractional	1.5938 in / mm
1-5/8"	Fractional	1.6250 in / mm
1-21/32"	Fractional	1.6562 in / mm
1-11/16"	Fractional	1.6875 in / mm
1-23/32"	Fractional	1.7188 in / mm
1-3/4"	Fractional	1.7500 in / mm
1-25/32"	Fractional	1.7812 in / mm
1-13/16"	Fractional	1.8125 in / mm
1-27/32"	Fractional	1.8438 in / mm
1-7/8"	Fractional	1.8750 in / mm
1-29/32"	Fractional	1.9062 in / mm
1-15/16"	Fractional	1.9375 in / mm
1-31/32"	Fractional	1.9688 in / mm
2"	Fractional	2.0000 in / mm

352 sizes · 4 systems · a size lists only the sizes within 0.002 in of itself

Which system is which

Fractional — 1/64″ steps up to 1″, then 1/32″. The default in US shops.
Number — #80 (0.0135″) down to #1 (0.2280″). Counterintuitively, higher number = smaller bit.
Letter — A (0.2340″) through Z (0.4130″), filling the gap above the number set.
Metric — 0.1 mm steps. Increasingly the practical default even in inch shops.

On "interchangeable"

The last column lists sizes within 0.002″ of each other. That tolerance is fine for a clearance hole and wrong for anything that locates a part. If the hole will be reamed, tapped, or take a dowel pin, use the size the print calls for.

Take the table with you — CSV · JSON

Data source and method

Sizes: ANSI fractional, number, letter and metric drill sets — factual values published in every tool catalog.
Conversion: Exact: 1 in = 25.4 mm.
Equivalence: Computed pairwise: each size lists only those within 0.002 in of itself. An earlier chain-linked version was rejected because a run of individually-compliant steps accumulated into spans far outside the tolerance.
Verification: Cross-system pairs confirmed to the fourth decimal: 1/4″ = E = 6.35 mm exactly; #7 (0.2010″) vs 5.1 mm (0.2008″) differ by 0.0002″. A generation-time assertion rejects the whole dataset if any listed pair exceeds the 0.002 in tolerance.
Original work: The four-system merge, diameter sort and equivalence grouping are this site's editorial structure, not a reproduction of any published table.

Related charts

Tap drill size chart — which of these bits to use before tapping
Thread size chart — the thread geometry behind those numbers