This drill bit size chart provides a list of sizes in several measurement systems, including fractional, metric, wire gauge number, and letter.
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Drill size
Diameter (in)
Diameter (mm)
1/64 in
0.
0.
1/32 in
0.
0.
3/64 in
0.
1.
1/16 in
0.
1.
5/64 in
0.
1.
3/32 in
0.
2.
7/64 in
0.
2.
1/8 in
0.125
3.175
9/64 in
0.
3.
5/32 in
0.
3.
11/64 in
0.
4.
3/16 in
0.
4.
13/64 in
0.
5.
7/32 in
0.
5.
15/64 in
0.
5.
1/4 in
0.25
6.35
17/64 in
0.
6.
9/32 in
0.
7.
19/64 in
0.
7.
5/16 in
0.
7.
21/64 in
0.
8.
11/32 in
0.
8.
23/64 in
0.
9.
3/8 in
0.375
9.525
25/64 in
0.
9.
13/32 in
0.
10.
27/64 in
0.
10.
7/16 in
0.
11.
29/64 in
0.
11.
15/32 in
0.
11.
31/64 in
0.
12.
1/2 in
0.5
12.7
33/64 in
0.
13.
17/32 in
0.
13.
35/64 in
0.
13.
9/16 in
0.
14.
37/64 in
0.
14.
19/32 in
0.
15.
39/64 in
0.
15.
5/8 in
0.625
15.875
41/64 in
0.
16.
43/64 in
0.
17.
11/16 in
0.
17.
45/64 in
0.
17.
23/32 in
0.
18.
47/64 in
0.
18.
3/4 in
0.75
19.05
49/64 in
0.
19.
25/32 in
0.
19.
51/64 in
0.
20.
13/16 in
0.
20.
53/64 in
0.
21.
27/32 in
0.
21.
55/64 in
0.
21.
7/8 in
0.875
22.225
57/64 in
0.
22.
29/32 in
0.
23.
21/23 in
0.913
23.
59/64 in
0.
23.
15/16 in
0.
23.
61/64 in
0.
24.
31/32 in
0.
24.
63/64 in
0.
25.
1 in
1
25.4
1 1/64 in
1.
25.
1 1/32 in
1.
26.
1 3/64 in
1.
26.
1 1/16 in
1.
26.
1 5/64 in
1.
27.
1 3/32 in
1.
27.
1 7/64 in
1.
28.
1 1/8 in
1.125
28.575
1 9/64 in
1.
28.
1 5/32 in
1.
29.
1 11/64 in
1.
29.
1 3/16 in
1.
30.
1 13/64 in
1.
30.
1 7/32 in
1.
30.
1 15/64 in
1.
31.
1 1/4 in
1.25
31.75
1 17/64 in
1.
32.
1 9/32 in
1.
32.
1 19/64 in
1.
32.
1 5/16 in
1.
33.
1 21/64 in
1.
33.
1 11/32 in
1.
34.
1 23/64 in
1.
34.
1 3/8 in
1.375
34.925
1 25/64 in
1.
35.
1 13/32 in
1.
35.
1 27/64 in
1.
36.
1 7/16 in
1.
36.
1 29/64 in
1.
36.
1 15/32 in
1.
37.
1 31/64 in
1.
37.
1 1/2 in
1.5
38.1
Drill size
Diameter (in)
Diameter (mm)
0.05 mm
0.002
0.05
0.1 mm
0.
0.1
0.2 mm
0.
0.2
0.3 mm
0.
0.3
0.4 mm
0.
0.4
0.5 mm
0.
0.5
0.6 mm
0.
0.6
0.7 mm
0.
0.7
0.8 mm
0.
0.8
0.9 mm
0.
0.9
1 mm
0.
1
1.1 mm
0.
1.1
1.2 mm
0.
1.2
1.3 mm
0.
1.3
1.4 mm
0.
1.4
1.5 mm
0.
1.5
1.6 mm
0.063
1.6
1.7 mm
0.
1.7
1.8 mm
0.
1.8
1.9 mm
0.
1.9
2 mm
0.
2
2.1 mm
0.
2.1
2.2 mm
0.
2.2
2.3 mm
0.
2.3
2.4 mm
0.
2.4
2.5 mm
0.
2.5
2.6 mm
0.
2.6
2.7 mm
0.
2.7
2.8 mm
0.
2.8
2.9 mm
0.
2.9
3 mm
0.
3
3.1 mm
0.
3.1
3.2 mm
0.126
3.2
3.3 mm
0.
3.3
3.4 mm
0.
3.4
3.5 mm
0.
3.5
3.6 mm
0.
3.6
3.7 mm
0.
3.7
3.8 mm
0.
3.8
3.9 mm
0.
3.9
4 mm
0.
4
4.1 mm
0.
4.1
4.2 mm
0.
4.2
4.3 mm
0.
4.3
4.4 mm
0.
4.4
4.5 mm
0.
4.5
4.6 mm
0.
4.6
4.7 mm
0.185
4.7
4.8 mm
0.189
4.8
4.9 mm
0.
4.9
5 mm
0.
5
5.1 mm
0.
5.1
5.2 mm
0.
5.2
5.3 mm
0.
5.3
5.4 mm
0.
5.4
5.5 mm
0.
5.5
5.6 mm
0.
5.6
5.7 mm
0.
5.7
5.8 mm
0.
5.8
5.9 mm
0.
5.9
6 mm
0.
6
6.1 mm
0.
6.1
6.2 mm
0.
6.2
6.3 mm
0.248
6.3
6.4 mm
0.252
6.4
6.5 mm
0.
6.5
6.6 mm
0.
6.6
6.7 mm
0.
6.7
6.8 mm
0.
6.8
6.9 mm
0.
6.9
7 mm
0.
7
7.1 mm
0.
7.1
7.2 mm
0.
7.2
7.3 mm
0.
7.3
7.4 mm
0.
7.4
7.5 mm
0.
7.5
7.6 mm
0.
7.6
7.7 mm
0.
7.7
7.8 mm
0.
7.8
7.9 mm
0.311
7.9
8 mm
0.315
8
8.1 mm
0.
8.1
8.2 mm
0.
8.2
8.3 mm
0.
8.3
8.4 mm
0.
8.4
8.5 mm
0.
8.5
8.6 mm
0.
8.6
8.7 mm
0.
8.7
8.8 mm
0.
8.8
8.9 mm
0.
8.9
9 mm
0.
9
9.1 mm
0.
9.1
9.2 mm
0.
9.2
9.3 mm
0.
9.3
9.4 mm
0.
9.4
9.5 mm
0.374
9.5
9.6 mm
0.378
9.6
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9.7 mm
0.
9.7
9.8 mm
0.
9.8
9.9 mm
0.
9.9
10 mm
0.
10
10.5 mm
0.
10.5
11 mm
0.
11
11.5 mm
0.
11.5
12 mm
0.
12
12.5 mm
0.
12.5
13 mm
0.
13
13.5 mm
0.
13.5
14 mm
0.
14
14.5 mm
0.
14.5
15 mm
0.
15
15.5 mm
0.
15.5
16 mm
0.
16
16.5 mm
0.
16.5
17 mm
0.
17
17.5 mm
0.689
17.5
18 mm
0.
18
18.5 mm
0.
18.5
19 mm
0.748
19
19.5 mm
0.
19.5
20 mm
0.
20
20.5 mm
0.
20.5
21 mm
0.
21
21.5 mm
0.
21.5
22 mm
0.
22
22.5 mm
0.
22.5
23 mm
0.
23
23.5 mm
0.
23.5
24 mm
0.
24
24.5 mm
0.
24.5
25 mm
0.
25
25.5 mm
1.
25.5
26 mm
1.
26
26.5 mm
1.
26.5
27 mm
1.063
27
27.5 mm
1.
27.5
28 mm
1.
28
28.5 mm
1.
28.5
29 mm
1.
29
29.5 mm
1.
29.5
30 mm
1.
30
30.5 mm
1.
30.5
31 mm
1.
31
31.5 mm
1.
31.5
32 mm
1.
32
32.5 mm
1.
32.5
33 mm
1.
33
33.5 mm
1.
33.5
34 mm
1.
34
34.5 mm
1.
34.5
35 mm
1.378
35
35.5 mm
1.
35.5
36 mm
1.
36
36.5 mm
1.437
36.5
37 mm
1.
37
37.5 mm
1.
37.5
38 mm
1.
38
Drill
Inch
mm
A
0.234
5.94
B
0.238
6.05
C
0.242
6.15
D
0.246
6.25
E
0.25
6.35
F
0.257
6.53
G
0.261
6.63
H
0.266
6.76
I
0.272
6.91
J
0.277
7.04
K
0.281
7.14
L
0.29
7.37
M
0.295
7.49
N
0.302
7.67
O
0.316
8.03
P
0.323
8.2
Q
0.332
8.43
R
0.339
8.61
S
0.348
8.84
T
0.358
9.09
U
0.368
9.35
V
0.377
9.58
W
0.386
9.8
X
0.397
10.08
Y
0.404
10.26
Z
0.413
10.49
Drill size
Diameter (in)
Diameter (mm)
#107
0.
0.
#106
0.
0.
#105
0.
0.
#104
0.
0.
#103
0.
0.
#102
0.
0.
#101
0.
0.
#100
0.
0.
#99
0.
0.
#98
0.
0.
#97
0.
0.
#96
0.
0.16
#95
0.
0.
#94
0.
0.
#93
0.
0.
#92
0.
0.
#91
0.
0.
#90
0.
0.221
#89
0.
0.
#88
0.
0.
#87
0.01
0.254
#86
0.
0.
#85
0.011
0.
#84
0.
0.
#83
0.012
0.
#82
0.
0.
#81
0.013
0.
#80
0.
0.
#79
0.
0.368
#78
0.016
0.
#77
0.018
0.
#76
0.02
0.508
#75
0.021
0.
#74
0.
0.
#73
0.024
0.
#72
0.025
0.635
#71
0.026
0.
#70
0.028
0.
#69
0.
0.
#68
0.031
0.
#67
0.032
0.
#66
0.033
0.
#65
0.035
0.889
#64
0.036
0.
#63
0.037
0.
#62
0.038
0.
#61
0.039
0.
#60
0.04
1.016
#59
0.041
1.
#58
0.042
1.
#57
0.043
1.
#56
0.
1.
#55
0.052
1.
#54
0.055
1.397
#53
0.
1.
#52
0.
1.
#51
0.067
1.
#50
0.07
1.778
#49
0.073
1.
#48
0.076
1.
#47
0.
1.
#46
0.081
2.
#45
0.082
2.
#44
0.086
2.
#43
0.089
2.
#42
0.
2.
#41
0.096
2.
#40
0.098
2.
#39
0.
2.
#38
0.
2.
#37
0.104
2.
#36
0.
2.
#35
0.11
2.794
#34
0.111
2.
#33
0.113
2.
#32
0.116
2.
#31
0.12
3.048
#30
0.
3.
#29
0.136
3.
#28
0.
3.
#27
0.144
3.
#26
0.147
3.
#25
0.
3.
#24
0.152
3.
#23
0.154
3.
#22
0.157
3.
#21
0.159
4.
#20
0.161
4.
#19
0.166
4.
#18
0.
4.
#17
0.173
4.
#16
0.177
4.
#15
0.18
4.572
#14
0.182
4.
#13
0.185
4.699
#12
0.189
4.
#11
0.191
4.
#10
0.
4.
#9
0.196
4.
#8
0.199
5.
#7
0.201
5.
#6
0.204
5.
#5
0.
5.
#4
0.209
5.
#3
0.213
5.
#2
0.221
5.
#1
0.228
5.
The drill size chart provides a list of standard size drill bits in several measurement systems, including fractional, metric, wire gauge number, and letter. The decimal equivalents of the diameters are shown in both English and Metric units. Fractional sizes are measured in inches, while metric sizes are measured in millimeters. The wire gauge and letter systems refer to tool diameters that increase as the wire gauge decreases from #107 to #1 and then continues from A to Z. The drill size chart contains tools up to 1.5 inches in diameter, but larger tools are also commonly used.
Downloadable versions:
Drill size standard:
Fractional Letter Wire Gauge MetricAre you interested in learning more about DTH drill pipes? Contact us today to secure an expert consultation!