Guide to Drill Sizes | Partners Knowledge Base

Standard Drill Sizes

When it comes to CNC machining, selecting the correct drill size is a critical factor that directly impacts the quality, precision, and efficiency of the final product. Standard drill sizes refer to the commonly used diameters of drill bits that are widely accepted across the manufacturing industry. Understanding these sizes helps ensure that machined components meet their design specifications, achieve the desired tolerances, and maintain structural integrity.

In this guide, we will explore the various standard drill size charts, explain their significance, and provide insights into how choosing the right drill size can enhance the overall quality of CNC machining projects.

Standard Drill Sizes Metric

Drill size	Diameter (in)	Diameter (mm)
0.05 mm	0.0020	0.0500
0.1 mm	0.0039	0.1000
0.2 mm	0.0079	0.2000
0.3 mm	0.0118	0.3000
0.4 mm	0.0158	0.4000
0.5 mm	0.0197	0.5000
0.6 mm	0.0236	0.6000
0.7 mm	0.0276	0.7000
0.8 mm	0.0315	0.8000
0.9 mm	0.0354	0.9000
1 mm	0.0394	1.0000
1.1 mm	0.0433	1.1000
1.2 mm	0.0472	1.2000
1.3 mm	0.0512	1.3000
1.4 mm	0.0551	1.4000
1.5 mm	0.0591	1.5000
1.6 mm	0.0630	1.6000
1.7 mm	0.0669	1.7000
1.8 mm	0.0709	1.8000
1.9 mm	0.0748	1.9000
2 mm	0.0787	2.0000
2.1 mm	0.0827	2.1000
2.2 mm	0.0866	2.2000
2.3 mm	0.0906	2.3000
2.4 mm	0.0945	2.4000
2.5 mm	0.0984	2.5000
2.6 mm	0.1024	2.6000
2.7 mm	0.1063	2.7000
2.8 mm	0.1102	2.8000
2.9 mm	0.1142	2.9000
3 mm	0.1181	3.0000
3.1 mm	0.1221	3.1000
3.2 mm	0.1260	3.2000
3.3 mm	0.1299	3.3000
3.4 mm	0.1339	3.4000
3.5 mm	0.1378	3.5000
3.6 mm	0.1417	3.6000
3.7 mm	0.1457	3.7000
3.8 mm	0.1496	3.8000
3.9 mm	0.1535	3.9000
4 mm	0.1575	4.0000
4.1 mm	0.1614	4.1000
4.2 mm	0.1654	4.2000
4.3 mm	0.1693	4.3000
4.4 mm	0.1732	4.4000
4.5 mm	0.1772	4.5000
4.6 mm	0.1811	4.6000
4.7 mm	0.1850	4.7000
4.8 mm	0.1890	4.8000
4.9 mm	0.1929	4.9000
5 mm	0.1969	5.0000
5.1 mm	0.2008	5.1000
5.2 mm	0.2047	5.2000
5.3 mm	0.2087	5.3000
5.4 mm	0.2126	5.4000
5.5 mm	0.2165	5.5000
5.6 mm	0.2205	5.6000
5.7 mm	0.2244	5.7000
5.8 mm	0.2284	5.8000
5.9 mm	0.2323	5.9000
6 mm	0.2362	6.0000
6.1 mm	0.2402	6.1000
6.2 mm	0.2441	6.2000
6.3 mm	0.2480	6.3000
6.4 mm	0.2520	6.4000
6.5 mm	0.2559	6.5000
6.6 mm	0.2598	6.6000
6.7 mm	0.2638	6.7000
6.8 mm	0.2677	6.8000
6.9 mm	0.2717	6.9000
7 mm	0.2756	7.0000
7.1 mm	0.2795	7.1000
7.2 mm	0.2835	7.2000
7.3 mm	0.2874	7.3000
7.4 mm	0.2913	7.4000
7.5 mm	0.2953	7.5000
7.6 mm	0.2992	7.6000
7.7 mm	0.3032	7.7000
7.8 mm	0.3071	7.8000
7.9 mm	0.3110	7.9000
8 mm	0.3150	8.0000
8.1 mm	0.3189	8.1000
8.2 mm	0.3228	8.2000
8.3 mm	0.3268	8.3000
8.4 mm	0.3307	8.4000
8.5 mm	0.3347	8.5000
8.6 mm	0.3386	8.6000
8.7 mm	0.3425	8.7000
8.8 mm	0.3465	8.8000
8.9 mm	0.3504	8.9000
9 mm	0.3543	9.0000
9.1 mm	0.3583	9.1000
9.2 mm	0.3622	9.2000
9.3 mm	0.3661	9.3000
9.4 mm	0.3701	9.4000
9.5 mm	0.3740	9.5000
9.6 mm	0.3780	9.6000
9.7 mm	0.3819	9.7000
9.8 mm	0.3858	9.8000
9.9 mm	0.3898	9.9000
10 mm	0.3937	10.0000
10.5 mm	0.4134	10.5000
11 mm	0.4331	11.0000
11.5 mm	0.4528	11.5000
12 mm	0.4724	12.0000
12.5 mm	0.4921	12.5000
13 mm	0.5118	13.0000
13.5 mm	0.5315	13.5000
14 mm	0.5512	14.0000
14.5 mm	0.5709	14.5000
15 mm	0.5906	15.0000
15.5 mm	0.6102	15.5000
16 mm	0.6299	16.0000
16.5 mm	0.6496	16.5000
17 mm	0.6693	17.0000
17.5 mm	0.6890	17.5000
18 mm	0.7087	18.0000
18.5 mm	0.7284	18.5000
19 mm	0.7480	19.0000
19.5 mm	0.7677	19.5000
20 mm	0.7874	20.0000
20.5 mm	0.8071	20.5000
21 mm	0.8268	21.0000
21.5 mm	0.8465	21.5000
22 mm	0.8661	22.0000
22.5 mm	0.8858	22.5000
23 mm	0.9055	23.0000
23.5 mm	0.9252	23.5000
24 mm	0.9449	24.0000
24.5 mm	0.9646	24.5000
25 mm	0.9843	25.0000
25.5 mm	1.0039	25.5000
26 mm	1.0236	26.0000
26.5 mm	1.0433	26.5000
27 mm	1.0630	27.0000
27.5 mm	1.0827	27.5000
28 mm	1.1024	28.0000
28.5 mm	1.1221	28.5000
29 mm	1.1417	29.0000
29.5 mm	1.1614	29.5000
30 mm	1.1811	30.0000
30.5 mm	1.2008	30.5000
31 mm	1.2205	31.0000
31.5 mm	1.2402	31.5000
32 mm	1.2598	32.0000
32.5 mm	1.2795	32.5000
33 mm	1.2992	33.0000
33.5 mm	1.3189	33.5000
34 mm	1.3386	34.0000
34.5 mm	1.3583	34.5000
35 mm	1.3780	35.0000
35.5 mm	1.3976	35.5000
36 mm	1.4173	36.0000
36.5 mm	1.4370	36.5000
37 mm	1.4567	37.0000
37.5 mm	1.4764	37.5000
38 mm	1.4961	38.0000

Drill Sizes (Letter)

Drill size	Diameter (in)	Diameter (mm)
A	0.2340	5.9436
B	0.2380	6.0452
C	0.2420	6.1468
D	0.2460	6.2484
E	0.2500	6.3500
F	0.2570	6.5278
G	0.2610	6.6294
H	0.2660	6.7564
I	0.2720	6.9088
J	0.2770	7.0358
K	0.2810	7.1374
L	0.2900	7.3660
M	0.2950	7.4930
N	0.3020	7.6708
O	0.3160	8.0264
P	0.3230	8.2042
Q	0.3320	8.4328
R	0.3390	8.6106
S	0.3480	8.8392
T	0.3580	9.0932
U	0.3680	9.3472
V	0.3770	9.5758
W	0.3860	9.8044
X	0.3970	10.0838
Y	0.4040	10.2616
Z	0.4130	10.4902

Drill Sizes (Fractional)

Drill size	Diameter (in)	Diameter (mm)
1/64 in	0.0156	0.3969
1/32 in	0.0313	0.7938
3/64 in	0.0469	1.1906
1/16 in	0.0625	1.5875
5/64 in	0.0781	1.9844
3/32 in	0.0938	2.3813
7/64 in	0.1094	2.7781
1/8 in	0.1250	3.1750
9/64 in	0.1406	3.5719
5/32 in	0.1563	3.9688
11/64 in	0.1719	4.3656
3/16 in	0.1875	4.7625
13/64 in	0.2031	5.1594
7/32 in	0.2188	5.5563
15/64 in	0.2344	5.9531
1/4 in	0.2500	6.3500
17/64 in	0.2656	6.7469
9/32 in	0.2813	7.1438
19/64 in	0.2969	7.5406
5/16 in	0.3125	7.9375
21/64 in	0.3281	8.3344
11/32 in	0.3438	8.7313
23/64 in	0.3594	9.1281
3/8 in	0.3750	9.5250
25/64 in	0.3906	9.9219
13/32 in	0.4063	10.3188
27/64 in	0.4219	10.7156
7/16 in	0.4375	11.1125
29/64 in	0.4531	11.5094
15/32 in	0.4688	11.9063
31/64 in	0.4844	12.3031
1/2 in	0.5000	12.7000
33/64 in	0.5156	13.0969
17/32 in	0.5313	13.4938
35/64 in	0.5469	13.8906
9/16 in	0.5625	14.2875
37/64 in	0.5781	14.6844
19/32 in	0.5938	15.0813
39/64 in	0.6094	15.4781
5/8 in	0.6250	15.8750
41/64 in	0.6406	16.2719
43/64 in	0.6719	17.0656
11/16 in	0.6875	17.4625
45/64 in	0.7031	17.8594
23/32 in	0.7188	18.2563
47/64 in	0.7344	18.6531
3/4 in	0.7500	19.0500
49/64 in	0.7656	19.4469
25/32 in	0.7813	19.8438
51/64 in	0.7969	20.2406
13/16 in	0.8125	20.6375
53/64 in	0.8281	21.0344
27/32 in	0.8438	21.4313
55/64 in	0.8594	21.8281
7/8 in	0.8750	22.2250
57/64 in	0.8906	22.6219
29/32 in	0.9063	23.0188
21/23 in	0.9130	23.1913
59/64 in	0.9219	23.4156
15/16 in	0.9375	23.8125
61/64 in	0.9531	24.2094
31/32 in	0.9688	24.6063
63/64 in	0.9844	25.0031
1 in	1.0000	25.4000
1 1/64 in	1.0156	25.7969
1 1/32 in	1.0313	26.1938
1 3/64 in	1.0469	26.5906
1 1/16 in	1.0625	26.9875
1 5/64 in	1.0781	27.3844
1 3/32 in	1.0938	27.7813
1 7/64 in	1.1094	28.1781
1 1/8 in	1.1250	28.5750
1 9/64 in	1.1406	28.9719
1 5/32 in	1.1563	29.3688
1 11/64 in	1.1719	29.7656
1 3/16 in	1.1875	30.1625
1 13/64 in	1.2031	30.5594
1 7/32 in	1.2188	30.9563
1 15/64 in	1.2344	31.3531
1 1/4 in	1.2500	31.7500
1 17/64 in	1.2656	32.1469
1 9/32 in	1.2813	32.5438
1 19/64 in	1.2969	32.9406
1 5/16 in	1.3125	33.3375
1 21/64 in	1.3281	33.7344
1 11/32 in	1.3438	34.1313
1 23/64 in	1.3594	34.5281
1 3/8 in	1.3750	34.9250
1 25/64 in	1.3906	35.3219
1 13/32 in	1.4063	35.7188
1 27/64 in	1.4219	36.1156
1 7/16 in	1.4375	36.5125
1 29/64 in	1.4531	36.9094
1 15/32 in	1.4688	37.3063
1 31/64 in	1.4844	37.7031
1 1/2 in	1.5000	38.1000

Drill Sizes (Wire Gauge)

Drill size	Diameter (in)	Diameter (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
#91	0.0083	0.2108
#90	0.0087	0.2210
#89	0.0091	0.2311
#88	0.0095	0.2413
#87	0.0100	0.2540
#86	0.0105	0.2667
#85	0.0110	0.2794
#84	0.0115	0.2921
#83	0.0120	0.3048
#82	0.0125	0.3175
#81	0.0130	0.3302
#80	0.0135	0.3429
#79	0.0145	0.3680
#78	0.0160	0.4064
#77	0.0180	0.4572
#76	0.0200	0.5080
#75	0.0210	0.5334
#74	0.0225	0.5715
#73	0.0240	0.6096
#72	0.0250	0.6350
#71	0.0260	0.6604
#70	0.0280	0.7112
#69	0.0292	0.7417
#68	0.0310	0.7874
#67	0.0320	0.8128
#66	0.0330	0.8382
#65	0.0350	0.8890
#64	0.0360	0.9144
#63	0.0370	0.9398
#62	0.0380	0.9652
#61	0.0390	0.9906
#60	0.0400	1.0160
#59	0.0410	1.0414
#58	0.0420	1.0668
#57	0.0430	1.0922
#56	0.0465	1.1811
#55	0.0520	1.3208
#54	0.0550	1.3970
#53	0.0595	1.5113
#52	0.0635	1.6129
#51	0.0670	1.7018
#50	0.0700	1.7780
#49	0.0730	1.8542
#48	0.0760	1.9304
#47	0.0785	1.9939
#46	0.0810	2.0574
#45	0.0820	2.0828
#44	0.0860	2.1844
#43	0.0890	2.2606
#42	0.0935	2.3749
#41	0.0960	2.4384
#40	0.0980	2.4892
#39	0.0995	2.5273
#38	0.1015	2.5781
#37	0.1040	2.6416
#36	0.1065	2.7051
#35	0.1100	2.7940
#34	0.1110	2.8194
#33	0.1130	2.8702
#32	0.1160	2.9464
#31	0.1200	3.0480
#30	0.1285	3.2639
#29	0.1360	3.4544
#28	0.1405	3.5687
#27	0.1440	3.6576
#26	0.1470	3.7338
#25	0.1495	3.7973
#24	0.1520	3.8608
#23	0.1540	3.9116
#22	0.1570	3.9878
#21	0.1590	4.0386
#20	0.1610	4.0894
#19	0.1660	4.2164
#18	0.1695	4.3053
#17	0.1730	4.3942
#16	0.1770	4.4958
#15	0.1800	4.5720
#14	0.1820	4.6228
#13	0.1850	4.6990
#12	0.1890	4.8006
#11	0.1910	4.8514
#10	0.1935	4.9149
#9	0.1960	4.9784
#8	0.1990	5.0546
#7	0.2010	5.1054
#6	0.2040	5.1816
#5	0.2055	5.2197
#4	0.2090	5.3086
#3	0.2130	5.4102
#2	0.2210	5.6134
#1	0.2280	5.7912

Guide to CNC Tapping (manufacturing Threads)

Standard Drill Sizes Metric

Drill Sizes (Letter)

Drill Sizes (Fractional)

Drill Sizes (Wire Gauge)