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Continuous Drill Bit Sizes

Measurement Systems
(Include: fractions, letters, wire gauge numbers and metric sizes

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Beyond 1/2

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 dispursed 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			Decimal
Bit Dia.		Equivalent
107			0.0019
106			0.0023
105			0.0027
104			0.0031
103			0.0035
102			0.0039
101			0.0043
100			0.0047
99			0.0051
98			0.0055
97			0.0059
96			0.0063
95			0.0067
94			0.0071
93			0.0075
92			0.0079
.2mm			0.0079
91			0.0083
90			0.0087
.22mm			0.0087
89			0.0091
88			0.0095
.25mm			0.0098
87			0.0100
86			0.0105
85			0.0110
.28mm			0.0110
84			0.0115
.3mm			0.0118
83			0.0120
82			0.0125
.32mm			0.0126
81			0.0130
80			0.0135
.35mm			0.0138
79			0.0145
1/64			0.0156
.4mm			0.0157
78			0.0160
.45mm			0.0177
77			0.0180
.5mm			0.0197
76			0.0200
75			0.0210
.55mm			0.0217
74			0.0225
.6mm			0.0236
73			0.0240
72			0.0250
.65mm			0.0256
71			0.0260
.7mm			0.0276
70			0.0280
69			0.0292
.75mm			0.0295
68			0.0310
1/32			0.0312
.8mm			0.0315
67			0.0320
66			0.0330
.85mm			0.0335
65			0.0350
.9mm			0.0354
64			0.0360
63			0.0370
.95mm			0.0374
62			0.0380
61			0.0390
1mm			0.0394
60			0.0400
59			0.0410
1.05mm			0.0413
58			0.0420
57			0.0430
1.1mm			0.0433
1.15mm			0.0453
56			0.0465
3/64			0.0469
1.2mm			0.0472
1.25mm			0.0492
1.3mm			0.0512
55			0.0520
1.35mm			0.0531
54			0.0550
1.4mm			0.0551
1.45mm			0.0571
1.5mm			0.0591
53			0.0595
1.55mm			0.0610
1/16			0.0625
52			0.0635
1.65mm			0.0650
1.7mm			0.0669
51			0.0670
1.75mm			0.0689
50			0.0700
1.8mm			0.0709
1.85mm			0.0728
49			0.0730
1.9mm			0.0748
48			0.0760
1.95mm			0.0768
5/64			0.0781
2mm			0.0787
2.05mm			0.0807
47			0.0785
46			0.0810
45			0.0820
2.1mm			0.0827
2.15mm			0.0846
44			0.0860
2.2mm			0.0866
2.25mm			0.0886
43			0.0890
2.3mm			0.0906
2.35mm			0.0925
42			0.0935
3/32			0.0938
2.4mm			0.0945
41			0.0960
2.45mm			0.0965
40			0.0980
2.5mm			0.0984
39			0.0995
38			0.1015
2.6mm			0.1024
37			0.1040
2.7mm			0.1063
36			0.1065
2.75mm			0.1083
7/64			0.1094
35			0.1100
2.8mm			0.1102
34			0.1110
33			0.1130
2.9mm			0.1142
32			0.1160
3mm			0.1181
31			0.1200

3.1mm			0.1181
1/8			0.1250
30			0.1285
3.3mm			0.1299
3.4mm			0.1339
29			0.1360
3.5mm			0.1378
28			0.1405
9/64			0.1406
3.6mm			0.1417
27			0.1440
3.7mm			0.1457
26			0.1470
3.75mm			0.1476
25			0.1495
3.8mm			0.1535
24			0.1520
3.9mm			0.1535
23			0.1540
5/32			0.1562
22			0.1570
4mm			0.1575
21			0.1590
20			0.1610
4.1mm			0.1614
4.2mm			0.1654
19			0.1660
4.25mm			0.1673
4.3mm			0.1693
18			0.1695
11/64			0.1719
17			0.1730
4.4mm			0.1732
16			0.1770
4.5mm			0.1772
15			0.1800
4.6mm			0.1811
14			0.1820
13			0.1850
4.7mm			0.1850
4.75mm			0.1870
3/16			0.1875
4.8mm			0.1890
12			0.1890
11			0.1910
4.9mm			0.1929
10			0.1935
9			0.1960
5.mm			0.1969
8			0.1990
5.1mm			0.2008
7			0.2010
13/64			0.2031
6			0.2040
5.2mm			0.2047
5			0.2055
5.25mm			0.2067
5.3mm			0.2087
4			0.2090
5.4mm			0.2126
3			0.2130
5.5mm			0.2165
7/32			0.2188
5.6mm			0.2205
2			0.2211
5.7mm			0.2244
5.75mm			0.2264
1			0.2280
5.8mm			0.2283
5.9mm			0.2323
A			0.2340
15/64			0.2344
6mm			0.2362
B			0.2380
6.1mm			0.2402
C			0.2420
6.2mm			0.2441
D			0.2460
6.25mm			0.2461
6.3mm			0.2480

1/4			0.2500
E			0.2500
6.4mm			0.2520
6.5mm			0.2559
F			0.2570
6.6mm			0.2598
G			0.2610
6.7mm			0.2638
17/64			0.2656
6.75mm			0.2657
H			0.2660
6.8mm			0.2677
6.9mm			0.2717
I			0.2720
7mm			0.2756
J			0.2770
7.1mm			0.2795
K			0.2810
9/32			0.2812
7.2mm			0.2835
7.25mm			0.2854
7.3mm			0.2874
L			0.2900
7.4mm			0.2913
M			0.2950
7.5mm			0.2953
19/64			0.2969
7.6mm			0.2992
N			0.3020
7.7mm			0.3031
7.75mm			0.3051
7.8mm			0.3071
7.9mm			0.3110
5/16			0.3125
8mm			0.3150
O			0.3160
8.1mm			0.3189
8.2mm			0.3228
P			0.3230
8.25mm			0.3248
8.3mm			0.3268
21/64			0.3281
8.4mm			0.3307
Q			0.3320
8.5mm			0.3346
8.6mm			0.3386
R			0.3390
8.7mm			0.3425
11/32			0.3438
8.75mm			0.3445
8.8mm			0.3465
S			0.3480
8.9mm			0.3504
9mm			0.3543
T			0.3580
9.1mm			0.3583
23/64			0.3594
9.2mm			0.3622
9.25mm			0.3642
9.3mm			0.3661
U			0.3680
9.4mm			0.3701
9.5mm			0.3740

3/8			0.3750
V			0.3770
9.6mm			0.3780
9.7mm			0.3819
9.75mm			0.3839
9.8mm			0.3858
W			0.3860
9.9mm			0.3898
25/64			0.3906
10mm			0.3937
X			0.3970	
Y			0.4040
13/32			0.4062
Z			0.4130
10.5mm			0.4134
27/64			0.4219
11mm			0.4331
7/16			0.4375
11.5mm			0.4528
29/64			0.4531
15/32			0.4688
12mm			0.4724
31/64			0.4844
1/2			0.5000

Beyond 1/2

13mm 0.5118 33/64 0.5156 17/32 0.5312 13.5mm 0.5315 35/64 0.5469 14mm 0.5512 9/16 0.5625 14.5mm 0.5709 37/64 0.5781 15mm 0.5906 19/32 0.5938 39/64 0.6094 15.5mm 0.6102 5/8 0.6250 16mm 0.6299 41/64 0.6406 16.5mm 0.6496 21/32 0.6562 17mm 0.6693 43/64 0.6719 11/16 0.6875 17.5mm 0.6890 45/64 0.7031 18mm 0.7087 23/32 0.7188 18.5mm 0.7283 47/64 0.7344 19mm 0.7480 3/4 0.7500 49/64 0.7656 19.5mm 0.7677 25/32 0.7812 20mm 0.7874 51/64 0.7969 20.5mm 0.8071 13/16 0.8125 21mm 0.8268 53/64 0.8281 27/32 0.8438 21.5mm 0.8465 55/64 0.8594 22mm 0.8661 7/8 0.8750 22.5mm 0.8858 57/64 0.8906 23mm 0.9055 29/32 0.9062 59/64 0.9219 23.5mm 0.9252 15/16 0.9375 24mm 0.9449 61/64 0.9531 24.5mm 0.9646 31/32 0.9688 25mm 0.9843 63/64 0.9844 1 1.0000

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