Standard Drill Sizes

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When designing drilled holes it is best practice to try to match standard drill sizes. The reference chart below helps understand what is considered a standard drill bit, starting from smallest to largest. Holes outside of this range may require specialized tooling. Depending on hole size, the feature may be pocket-milled with an endmill versus drilling.

Sizes on imperial drill kits are typically referenced by numbers or letters. Metric drill let's typically just used the actual measurement. The four-column chart below is a handy cross-reference for drill bit sizes.

Dirll Bit Size Reference Chart
0.0059" - 0.1015"   0.1024" - 0.2913"   0.2950" - 0.9843"   0.9844" - 2.0000"
Size Decimal Equivalent (in)   Size Decimal Equivalent (in)   Size Decimal Equivalent (in)   Size Decimal Equivalent (in)
97 0.0059   2.60 mm 0.1024   M 0.295   63/64" 0.9844
96 0.0063   37 0.104   7.50 mm 0.2953   1" 1
95 0.0067   2.70 mm 0.1063   19/64" 0.2969   25.50 mm 1.0039
94 0.0071   36 0.1065   7.60 mm 0.2992   1-1/64" 1.0156
93 0.0075   2.75 mm 0.1083   N 0.302   26.00 mm 1.0236
92 0.0079   7/64" 0.1094   7.70 mm 0.3031   1-1/32" 1.0312
91 0.0083   35 0.11   7.75 mm 0.3051   26.50 mm 1.0433
90 0.0087   2.80 mm 0.1102   7.80 mm 0.3071   1-3/64" 1.0469
89 0.0091   34 0.111   7.90 mm 0.311   1-1/16" 1.0625
88 0.0095   33 0.113   5/16" 0.3125   27.00 mm 1.063
.25 mm 0.0098   2.90 mm 0.1142   8.00 mm 0.315   1-5/64" 1.0781
87 0.01   32 0.116   O 0.316   27.50 mm 1.0827
86 0.0105   3.00 mm 0.1181   8.10 mm 0.3189   1-3/32" 1.0938
85 0.011   31 0.12   8.20 mm 0.3228   28.00 mm 1.1024
84 0.0115   3.10 mm 0.122   P 0.323   1-7/64" 1.1094
.30 mm 0.0118   1/8" 0.125   8.25 mm 0.3248   28.50 mm 1.122
83 0.012   3.20 mm 0.126   8.30 mm 0.3268   1-1/8" 1.125
82 0.0125   3.25 mm 0.128   21/64" 0.3281   1-9/64" 1.1406
.32 mm 0.0126   30 0.1285   8.40 mm 0.3307   29.00 mm 1.1417
81 0.013   3.30 mm 0.1299   Q 0.332   1-5/32" 1.1562
80 0.0135   3.40 mm 0.1339   8.50 mm 0.3346   29.50 mm 1.1614
.35 mm 0.0138   29 0.136   8.60 mm 0.3386   1-11/64" 1.1719
.36 mm 0.0142   3.50 mm 0.1378   R 0.339   30.00 mm 1.1811
79 0.0145   28 0.1405   8.70 mm 0.3425   1-3/16" 1.1875
.38 mm 0.015   9/64" 0.1406   11/32" 0.3438   30.50 mm 1.2008
1/64" 0.0156   3.60 mm 0.1417   8.75 mm 0.3445   1-13/64" 1.2031
.40 mm 0.0157   27 0.144   8.80 mm 0.3465   1-7/32" 1.2188
78 0.016   3.70 mm 0.1457   S 0.348   31.00 mm 1.2205
.42 mm 0.0165   26 0.147   8.90 mm 0.3504   1-15/64" 1.2344
.44 mm 0.0173   3.75 mm 0.1476   9.00 mm 0.3543   31.50 mm 1.2402
.45 mm 0.0177   25 0.1495   T 0.358   1-1/4" 1.25
77 0.018   3.80 mm 0.1496   9.10 mm 0.3583   32.00 mm 1.2598
.46 mm 0.0181   24 0.152   23/64" 0.3594   1-17/64" 1.2656
.48 mm 0.0189   3.90 mm 0.1535   9.20 mm 0.3622   32.50 mm 1.2795
.50 mm 0.0197   23 0.154   9.25 mm 0.3642   1-9/32" 1.2812
76 0.02   5/32" 0.1562   9.30 mm 0.3661   1-19/64" 1.2969
75 0.021   22 0.157   U 0.368   33.00 mm 1.2992
.55 mm 0.0217   4.00 mm 0.1575   9.40 mm 0.3701   1-5/16" 1.3125
74 0.0225   21 0.159   9.50 mm 0.374   33.50 mm 1.3189
.60 mm 0.0236   20 0.161   3/8" 0.375   1-21/64" 1.3281
73 0.024   4.10 mm 0.1614   V 0.377   34.00 mm 1.3386
72 0.025   4.20 mm 0.1654   9.60 mm 0.378   1-11/32" 1.3438
.65 mm 0.0256   19 0.166   9.70 mm 0.3819   34.50 mm 1.3583
71 0.026   4.25 mm 0.1673   9.75 mm 0.3839   1-23/64" 1.3594
.70 mm 0.0276   4.30 mm 0.1693   9.80 mm 0.3858   1-3/8" 1.375
70 0.028   18 0.1695   W 0.386   35.00 mm 1.378
69 0.0292   11/64" 0.1719   9.90 mm 0.3898   1-25/64" 1.3906
.75 mm 0.0295   17 0.173   25/64" 0.3906   35.50 mm 1.3976
68 0.031   4.40 mm 0.1732   10.00 mm 0.3937   1-13/32" 1.4062
1/32" 0.0312   16 0.177   X 0.397   36.00 mm 1.4173
.80 mm 0.0315   4.50 mm 0.1772   Y 0.404   1-27/64" 1.4219
67 0.032   15 0.18   13/32" 0.4062   36.50 mm 1.437
66 0.033   4.60 mm 0.1811   Z 0.413   1-7/16" 1.4375
.85 mm 0.0335   14 0.182   10.50 mm 0.4134   1-29/64" 1.4531
65 0.035   13 0.185   27/64" 0.4219   37.00 mm 1.4567
.90 mm 0.0354   4.70 mm 0.185   11.00 mm 0.4331   1-15/32" 1.4688
64 0.036   4.75 mm 0.187   7/16" 0.4375   37.50 mm 1.4764
63 0.037   3/16" 0.1875   11.50 mm 0.4528   1-31/64" 1.4844
.95 mm 0.0374   4.80 mm 0.189   29/64" 0.4531   38.00 mm 1.4961
62 0.038   12 0.189   15/32" 0.4688   1-1/2" 1.5
61 0.039   11 0.191   12.00 mm 0.4724   1-33/64" 1.5156
1.00 mm 0.0394   4.90 mm 0.1929   31/64" 0.4844   38.50 mm 1.5157
60 0.04   10 0.1935   12.50 mm 0.4921   1-17/32" 1.5312
59 0.041   9 0.196   1/2" 0.5   39.00 mm 1.5354
1.05 mm 0.0413   5.00 mm 0.1969   13.00 mm 0.5118   1-35/64" 1.5469
58 0.042   8 0.199   33/64" 0.5156   39.50 mm 1.5551
57 0.043   5.10 mm 0.2008   17/32" 0.5312   1-9/16" 1.5625
1.10 mm 0.0433   7 0.201   13.50 mm 0.5315   40.00 mm 1.5748
1.15 mm 0.0453   13/64" 0.2031   35/64" 0.5469   1-37/64" 1.5781
56 0.0465   6 0.204   14.00 mm 0.5512   1-19/32" 1.5938
3/64" 0.0469   5.20 mm 0.2047   9/16" 0.5625   40.50 mm 1.5945
1.20 mm 0.0472   5 0.2055   14.50 mm 0.5709   1-39/64" 1.6094
1.25 mm 0.0492   5.25 mm 0.2067   37/64" 0.5781   41.00 mm 1.6142
1.30 mm 0.0512   5.30 mm 0.2087   15.00 mm 0.5906   1-5/8" 1.625
55 0.052   4 0.209   19/32" 0.5938   41.50 mm 1.6339
1.35 mm 0.0531   5.40 mm 0.2126   39/64" 0.6094   1-41/64" 1.6406
54 0.055   3 0.213   15.50 mm 0.6102   42.00 mm 1.6535
1.40 mm 0.0551   5.50 mm 0.2165   5/8" 0.625   1-21/32" 1.6562
1.45 mm 0.0571   7/32" 0.2188   16.00 mm 0.6299   1-43/64" 1.6719
1.50 mm 0.0591   5.60 mm 0.2205   41/64" 0.6406   42.50 mm 1.6732
53 0.0595   2 0.221   16.50 mm 0.6496   1-11/16" 1.6875
1.55 mm 0.061   5.70 mm 0.2244   21/32" 0.6562   43.00 mm 1.6929
1/16" 0.0625   5.75 mm 0.2264   17.00 mm 0.6693   1-45/64" 1.7031
1.60 mm 0.063   1 0.228   43/64" 0.6719   43.50 mm 1.7126
52 0.0635   5.80 mm 0.2283   11/16" 0.6875   1-23/32" 1.7188
1.65 mm 0.065   5.90 mm 0.2323   17.50 mm 0.689   44.00 mm 1.7323
1.70 mm 0.0669   A 0.234   45/64" 0.7031   1-47/64" 1.7344
51 0.067   15/64" 0.2344   18.00 mm 0.7087   1-3/4" 1.75
1.75 mm 0.0689   6.00 mm 0.2362   23/32" 0.7188   44.50 mm 1.752
50 0.07   B 0.238   18.50 mm 0.7283   1-49/64" 1.7656
1.80 mm 0.0709   6.10 mm 0.2402   47/64" 0.7344   45.00 mm 1.7717
1.85 mm 0.0728   C 0.242   19.00 mm 0.748   1-25/32" 1.7812
49 0.073   6.20 mm 0.2441   3/4" 0.75   45.50 mm 1.7913
1.90 mm 0.0748   D 0.246   49/64" 0.7656   1-51/64" 1.7969
48 0.076   6.25 mm 0.2461   19.50 mm 0.7677   46.00 mm 1.811
1.95 mm 0.0768   6.30 mm 0.248   25/32" 0.7812   1-13/16" 1.8125
5/64" 0.0781   1/4" E 0.25   20.00 mm 0.7874   1-53/64" 1.8281
47 0.0785   6.40 mm 0.252   51/64" 0.7969   46.50 mm 1.8307
2.00 mm 0.0787   6.50 mm 0.2559   20.50 mm 0.8071   1-27/32" 1.8438
2.05 mm 0.0807   F 0.257   13/16" 0.8125   47.00 mm 1.8504
46 0.081   6.60 mm 0.2598   21.00 mm 0.8268   1-55/64" 1.8594
45 0.082   G 0.261   53/64" 0.8281   47.50 mm 1.8701
2.10 mm 0.0827   6.70 mm 0.2638   27/32" 0.8438   1-7/8" 1.875
2.15 mm 0.0846   17/64" 0.2656   21.50 mm 0.8465   48.00 mm 1.8898
44 0.086   6.75 mm 0.2657   55/64" 0.8594   1-57/64" 1.8906
2.20 mm 0.0866   H 0.266   22.00 mm 0.8661   1-29/32" 1.9062
2.25 mm 0.0886   6.80 mm 0.2677   7/8" 0.875   48.50 mm 1.9094
43 0.089   6.90 mm 0.2717   22.50 mm 0.8858   1-59/64" 1.9219
2.30 mm 0.0906   I 0.272   57/64" 0.8906   49.00 mm 1.9291
2.35 mm 0.0925   7.00 mm 0.2756   23.00 mm 0.9055   1-15/16" 1.9375
42 0.0935   J 0.277   29/32" 0.9062   49.50 mm 1.9488
3/32" 0.0938   7.10 mm 0.2795   59/64" 0.9219   1-61/64" 1.9531
2.40 mm 0.0945   K 0.281   23.50 mm 0.9252   50.00 mm 1.9685
41 0.096   9/32" 0.2812   15/16" 0.9375   1-31/32" 1.9688
2.45 mm 0.0965   7.20 mm 0.2835   24.00 mm 0.9449   1-63/64" 1.9844
40 0.098   7.25 mm 0.2854   61/64" 0.9531   50.50 mm 1.9882
2.50 mm 0.0984   7.30 mm 0.2874   24.50 mm 0.9646   2" 2
39 0.0995   L 0.29   31/32" 0.9688      
38 0.1015   7.40 mm 0.2913   25.00 mm 0.9843      

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