Think & Tinker, Ltd.
CNC router bits and carbide cutting tools with tutorials and technical guides

Drill Bit Diameter Conversion Chart

PreciseBits offers bits in the following diameter sizes

Drill
Number
Fractional
Inches
Decimal
Inches
mm
 
 
0.0050
0.13
97
 
0.0060
0.15
94
 
0.0070
0.18
89
 
0.0090
0.23
87
 
0.0100
0.25
83
 
0.0120
0.30
81
 
0.0130
0.33
 
 
0.0150
0.38
 
1/64
0.0156
0.40
78
 
0.0160
0.41
 
 
0.0170
0.43
77
 
0.0180
0.46
76
 
0.0200
0.51
72
 
0.0250
0.64
71
 
0.0260
0.66
68
 
0.0310
0.79
 
1/32
0.0313
0.80
65
 
0.0350
0.89
  
Drill
Number
Fractional
Inches
Decimal
Inches
mm
65
 
0.0350
0.89
62
 
0.0380
0.97
 
 
0.0394
1.00
60
 
0.0400
1.02
 
3/64
0.0469
1.19
 
 
0.0480
1.22
 
 
0.0500
1.27
 
 
0.0530
1.35
 
1/16
0.0625
1.59
52
 
0.0630
1.60
 
 
0.0787
2.00
 
3/32
0.0938
2.38
 
 
0.1181
3.00
 
1/8
0.1250
3.18
 
5/32
0.1562
3.97
22
 
0.1570
3.99
 
3/16
0.1875
4.76
 
1/4
0.2500
6.35