Drill Bit Sizes & Conversions Table

Drill Bit Size Conversion Table

Drill bits from zero to one half inch are sized in four ways; fractions, wire gauge numbers, letters, and metric in millimeters. You will see drill bits with a fraction, number, letter or metric number stamped on their shank indicating their size.

The fractions range from 1/64 inch to 32/64 inch. The numbers range from 107 (smallest) to 1 (largest). Where the number 1 drill bit leaves off the letter A (smallest) begins and continues through the letter Z (largest).

The metric sizes are dispersed throughout. All of these drill bits are different in size except for the 90 and .22mm which are both 0.0087 inches in diameter, the 85 and the .28mm which are both 0.0110 inches in diameter, the 13 and the 4.7mm which are both 0.1850 inches in diameter, the 4.8mm and the 12 which are both 0.1890 inches in diameter, and the 1/4 inch and letter E bits which are both 0.250 inches in diameter.

All of the drill bits are listed below with their decimal equivalents.

Drill Bit 		Decimal			Decimal
Size			(in.)			(mm)
107			0.0019			0.0483
106			0.0023			0.0584
105			0.0027			0.0686
104			0.0031			0.0787
103			0.0035			0.0889
102			0.0039			0.0991
101			0.0043			0.1092
100			0.0047			0.1194
99			0.0051			0.1295
98			0.0055			0.1397
97			0.0059			0.1499
96			0.0063			0.1600
95			0.0067			0.1702
94			0.0071			0.1803
93			0.0075			0.1905
92			0.0079			0.2007
.2mm			0.0079			0.2007
91			0.0083			0.2108
90			0.0087			0.2210
.22mm			0.0087			0.2210
89			0.0091			0.2311
88			0.0095			0.2413
.25mm			0.0098			0.2489
87			0.0100			0.2540
86			0.0105			0.2667
85			0.0110			0.2794
.28mm			0.0110			0.2794
84			0.0115			0.2921
.3mm			0.0118			0.2997
83			0.0120			0.3048
82			0.0125			0.3175
.32mm			0.0126			0.3200
81			0.0130			0.3302
80			0.0135			0.3429
.35mm			0.0138			0.3505
79			0.0145			0.3683
1/64			0.0156			0.3962
.4mm			0.0157			0.3988
78			0.0160			0.4064
.45mm			0.0177			0.4496
77			0.0180			0.4572
.5mm			0.0197			0.5004
76			0.0200			0.5080
75			0.0210			0.5334
.55mm			0.0217			0.5512
74			0.0225			0.5715
.6mm			0.0236			0.5994
73			0.0240			0.6096
72			0.0250			0.6350
.65mm			0.0256			0.6502
71			0.0260			0.6604
.7mm			0.0276			0.7010
70			0.0280			0.7112
69			0.0292			0.7417
.75mm			0.0295			0.7493
68			0.0310			0.7874
1/32			0.0312			0.7925
.8mm			0.0315			0.8001
67			0.0320			0.8128
66			0.0330			0.8382
.85mm			0.0335			0.8509
65			0.0350			0.8890
.9mm			0.0354			0.8992
64			0.0360			0.9144
63			0.0370			0.9398
.95mm			0.0374			0.9500
62			0.0380			0.9652
61			0.0390			0.9906
1mm			0.0394			1.0008
60			0.0400			1.0160
59			0.0410			1.0414
1.05mm			0.0413			1.0490
58			0.0420			1.0668
57			0.0430			1.0922
1.1mm			0.0433			1.0998
1.15mm			0.0453			1.1506
56			0.0465			1.1811
3/64			0.0469			1.1913
1.2mm			0.0472			1.1989
1.25mm			0.0492			1.2497
1.3mm			0.0512			1.3005
55			0.0520			1.3208
1.35mm			0.0531			1.3487
54			0.0550			1.3970
1.4mm			0.0551			1.3995
1.45mm			0.0571			1.4503
1.5mm			0.0591			1.5011
53			0.0595			1.5113
1.55mm			0.0610			1.5494
1/16			0.0625			1.5875
52			0.0635			1.6129
1.65mm			0.0650			1.6510
1.7mm			0.0669			1.6993
51			0.0670			1.7018
1.75mm			0.0689			1.7501
50			0.0700			1.7780
1.8mm			0.0709			1.8009
1.85mm			0.0728			1.8491
49			0.0730			1.8542
1.9mm			0.0748			1.8999
48			0.0760			1.9304
1.95mm			0.0768			1.9507
5/64			0.0781			1.9837
2mm			0.0787			1.9990
2.05mm			0.0807			2.0498
47			0.0785			1.9939
46			0.0810			2.0574
45			0.0820			2.0828
2.1mm			0.0827			2.1006
2.15mm			0.0846			2.1488
44			0.0860			2.1844
2.2mm			0.0866			2.1996
2.25mm			0.0886			2.2504
43			0.0890			2.2606
2.3mm			0.0906			2.3012
2.35mm			0.0925			2.3495
42			0.0935			2.3749
3/32			0.0938			2.3825
2.4mm			0.0945			2.4003
41			0.0960			2.4384
2.45mm			0.0965			2.4511
40			0.0980			2.4892
2.5mm			0.0984			2.4994
39			0.0995			2.5273
38			0.1015			2.5781
2.6mm			0.1024			2.6010
37			0.1040			2.6416
2.7mm			0.1063			2.7000
36			0.1065			2.7051
2.75mm			0.1083			2.7508
7/64			0.1094			2.7788
35			0.1100			2.7940
2.8mm			0.1102			2.7991
34			0.1110			2.8194
33			0.1130			2.8702
2.9mm			0.1142			2.9007
32			0.1160			2.9464
3mm			0.1181			2.9997
31			0.1200			3.0480
3.1mm			0.1181			2.9997
1/8			0.1250			3.1750
30			0.1285			3.2639
3.3mm			0.1299			3.2995
3.4mm			0.1339			3.4011
29			0.1360			3.4544
3.5mm			0.1378			3.5001
28			0.1405			3.5687
9/64			0.1406			3.5712
3.6mm			0.1417			3.5992
27			0.1440			3.6576
3.7mm			0.1457			3.7008
26			0.1470			3.7338
3.75mm			0.1476			3.7490
25			0.1495			3.7973
3.8mm			0.1535			3.8989
24			0.1520			3.8608
3.9mm			0.1535			3.8989
23			0.1540			3.9116
5/32			0.1562			3.9675
22			0.1570			3.9878
4mm			0.1575			4.0005
21			0.1590			4.0386
20			0.1610			4.0894
4.1mm			0.1614			4.0996
4.2mm			0.1654			4.2012
19			0.1660			4.2164
4.25mm			0.1673			4.2494
4.3mm			0.1693			4.3002
18			0.1695			4.3053
11/64			0.1719			4.3663
17			0.1730			4.3942
4.4mm			0.1732			4.3993
16			0.1770			4.4958
4.5mm			0.1772			4.5009
15			0.1800			4.5720
4.6mm			0.1811			4.5999
14			0.1820			4.6228
13			0.1850			4.6990
4.7mm			0.1850			4.6990
4.75mm			0.1870			4.7498
3/16			0.1875			4.7625
4.8mm			0.1890			4.8006
12			0.1890			4.8006
11			0.1910			4.8514
4.9mm			0.1929			4.8997
10			0.1935			4.9149
9			0.1960			4.9784
5.mm			0.1969			5.0013
8			0.1990			5.0546
5.1mm			0.2008			5.1003
7			0.2010			5.1054
13/64			0.2031			5.1587
6			0.2040			5.1816
5.2mm			0.2047			5.1994
5			0.2055			5.2197
5.25mm			0.2067			5.2502
5.3mm			0.2087			5.3010
4			0.2090			5.3086
5.4mm			0.2126			5.4000
3			0.2130			5.4102
5.5mm			0.2165			5.4991
7/32			0.2188			5.5575
5.6mm			0.2205			5.6007
2			0.2211			5.6159
5.7mm			0.2244			5.6998
5.75mm			0.2264			5.7506
1			0.2280			5.7912
5.8mm			0.2283			5.7988
5.9mm			0.2323			5.9004
A			0.2340			5.9436
15/64			0.2344			5.9538
6mm			0.2362			5.9995
B			0.2380			6.0452
6.1mm			0.2402			6.1011
C			0.2420			6.1468
6.2mm			0.2441			6.2001
D			0.2460			6.2484
6.25mm			0.2461			6.2509
6.3mm			0.2480			6.2992
1/4			0.2500			6.3500
E			0.2500			6.3500
6.4mm			0.2520			6.4008
6.5mm			0.2559			6.4999
F			0.2570			6.5278
6.6mm			0.2598			6.5989
G			0.2610			6.6294
6.7mm			0.2638			6.7005
17/64			0.2656			6.7462
6.75mm			0.2657			6.7488
H			0.2660			6.7564
6.8mm			0.2677			6.7996
6.9mm			0.2717			6.9012
I			0.2720			6.9088
7mm			0.2756			7.0002
J			0.2770			7.0358
7.1mm			0.2795			7.0993
K			0.2810			7.1374
9/32			0.2812			7.1425
7.2mm			0.2835			7.2009
7.25mm			0.2854			7.2492
7.3mm			0.2874			7.3000
L			0.2900			7.3660
7.4mm			0.2913			7.3990
M			0.2950			7.4930
7.5mm			0.2953			7.5006
19/64			0.2969			7.5413
7.6mm			0.2992			7.5997
N			0.3020			7.6708
7.7mm			0.3031			7.6987
7.75mm			0.3051			7.7495
7.8mm			0.3071			7.8003
7.9mm			0.3110			7.8994
5/16			0.3125			7.9375
8mm			0.3150			8.0010
O			0.3160			8.0264
8.1mm			0.3189			8.1001
8.2mm			0.3228			8.1991
P			0.3230			8.2042
8.25mm			0.3248			8.2499
8.3mm			0.3268			8.3007
21/64			0.3281			8.3337
8.4mm			0.3307			8.3998
Q			0.3320			8.4328
8.5mm			0.3346			8.4988
8.6mm			0.3386			8.6004
R			0.3390			8.6106
8.7mm			0.3425			8.6995
11/32			0.3438			8.7325
8.75mm			0.3445			8.7503
8.8mm			0.3465			8.8011
S			0.3480			8.8392
8.9mm			0.3504			8.9002
9mm			0.3543			8.9992
T			0.3580			9.0932
9.1mm			0.3583			9.1008
23/64			0.3594			9.1288
9.2mm			0.3622			9.1999
9.25mm			0.3642			9.2507
9.3mm			0.3661			9.2989
U			0.3680			9.3472
9.4mm			0.3701			9.4005
9.5mm			0.3740			9.4996
3/8			0.3750			9.5250
V			0.3770			9.5758
9.6mm			0.3780			9.6012
9.7mm			0.3819			9.7003
9.75mm			0.3839			9.7511
9.8mm			0.3858			9.7993
W			0.3860			9.8044
9.9mm			0.3898			9.9009
25/64			0.3906			9.9212
10mm			0.3937			10.0000
X			0.3970			10.0838
Y			0.4040			10.2616
13/32			0.4062			10.3175
Z			0.4130			10.4902
10.5mm			0.4134			10.5004
27/64			0.4219			10.7163
11mm			0.4331			11.0007
7/16			0.4375			11.1125
11.5mm			0.4528			11.5011
29/64			0.4531			11.5087
15/32			0.4688			11.9075
12mm			0.4724			11.9990
31/64			0.4844			12.3038
1/2			0.5000			12.7000
13mm			0.5118			12.9997
33/64			0.5156			13.0962
17/32			0.5312			13.4925
13.5mm			0.5315			13.5001
35/64			0.5469			13.8913
14mm			0.5512			14.0005
9/16			0.5625			14.2875
14.5mm			0.5709			14.5009
37/64			0.5781			14.6837
15mm			0.5906			15.0012
19/32			0.5938			15.0825
39/64			0.6094			15.4788
15.5mm			0.6102			15.4991
5/8			0.6250			15.8750
16mm			0.6299			15.9995
41/64			0.6406			16.2712
16.5mm			0.6496			16.4998
21/32			0.6562			16.6675
17mm			0.6693			17.0002
43/64			0.6719			17.0663
11/16			0.6875			17.4625
17.5mm			0.6890			17.5006
45/64			0.7031			17.8587
18mm			0.7087			18.0010
23/32			0.7188			18.2575
18.5mm			0.7283			18.4988
47/64			0.7344			18.6538
19mm			0.7480			18.9992
3/4			0.7500			19.0500
49/64			0.7656			19.4462
19.5mm			0.7677			19.4996
25/32			0.7812			19.8425
20mm			0.7874			20.0000
51/64			0.7969			20.2413
20.5mm			0.8071			20.5003
13/16			0.8125			20.6375
21mm			0.8268			21.0007
53/64			0.8281			21.0337
27/32			0.8438			21.4325
21.5mm			0.8465			21.5011
55/64			0.8594			21.8288
22mm			0.8661			21.9989
7/8			0.8750			22.2250
22.5mm			0.8858			22.4993
57/64			0.8906			22.6212
23mm			0.9055			22.9997
29/32			0.9062			23.0175
59/64			0.9219			23.4163
23.5mm			0.9252			23.5001
15/16			0.9375			23.8125
24mm			0.9449			24.0005
61/64			0.9531			24.2087
24.5mm			0.9646			24.5008
31/32			0.9688			24.6075
25mm			0.9843			25.0012
63/64			0.9844			25.0038
1			1.0000			25.4000

5 thoughts on “Drill Bit Sizes & Conversions Table

  1. Pingback: Tools for ultra-precise macro, micro, nano, and super nano builds

  2. Pingback: Tools for ultra-precise macro, micro, nano, and super nano builds

  3. Thank you. Very Helpful.
    Do you have a Table for Hole sizes and the Size of Drill Bits to use for Wood, Steel and Concrete?

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>