Drill Bit Size Chart (2025)

Table of Contents

Fractional Sizes (Standard) Letter Sizes Number Sizes Metric Sizes (Common) Subscribe to the Mech Lab!

This drill bit size chart includes three main categorization systems:

Fractional Sizes – The standard imperial measurements (1/64″, 1/32″, etc.) with their decimal inch and metric (mm) equivalents.
Letter Sizes – These range from A to Z, with corresponding decimal inch and metric conversions.
Number Sizes – These range from #1 (largest) to #80 (smallest), commonly used for precision work.
Metric Sizes – The most common metric drill bit sizes with their decimal inch equivalents.

Fractional Sizes (Standard)

Fraction (inches)	Decimal (inches)	Metric (mm)
1/64	0.0156	0.397
1/32	0.0313	0.794
3/64	0.0469	1.191
1/16	0.0625	1.588
5/64	0.0781	1.984
3/32	0.0938	2.381
7/64	0.1094	2.778
1/8	0.1250	3.175
9/64	0.1406	3.572
5/32	0.1563	3.969
11/64	0.1719	4.366
3/16	0.1875	4.763
13/64	0.2031	5.159
7/32	0.2188	5.556
15/64	0.2344	5.953
1/4	0.2500	6.350
17/64	0.2656	6.747
9/32	0.2813	7.144
19/64	0.2969	7.541
5/16	0.3125	7.938
21/64	0.3281	8.334
11/32	0.3438	8.731
23/64	0.3594	9.128
3/8	0.3750	9.525
25/64	0.3906	9.922
13/32	0.4063	10.319
27/64	0.4219	10.716
7/16	0.4375	11.113
29/64	0.4531	11.509
15/32	0.4688	11.906
31/64	0.4844	12.303
1/2	0.5000	12.700
33/64	0.5156	13.097
17/32	0.5313	13.494
35/64	0.5469	13.891
9/16	0.5625	14.288
37/64	0.5781	14.684
19/32	0.5938	15.081
39/64	0.6094	15.478
5/8	0.6250	15.875
41/64	0.6406	16.272
21/32	0.6563	16.669
43/64	0.6719	17.066
11/16	0.6875	17.463
45/64	0.7031	17.859
23/32	0.7188	18.256
47/64	0.7344	18.653
3/4	0.7500	19.050
49/64	0.7656	19.447
25/32	0.7813	19.844
51/64	0.7969	20.241
13/16	0.8125	20.638
53/64	0.8281	21.034
27/32	0.8438	21.431
55/64	0.8594	21.828
7/8	0.8750	22.225
57/64	0.8906	22.622
29/32	0.9063	23.019
59/64	0.9219	23.416
15/16	0.9375	23.813
61/64	0.9531	24.209
31/32	0.9688	24.606
63/64	0.9844	25.003
1	1.0000	25.400

Letter Sizes

Letter	Decimal (inches)	Metric (mm)
A	0.234	5.944
B	0.238	6.045
C	0.242	6.147
D	0.246	6.248
E	0.250	6.350
F	0.257	6.528
G	0.261	6.629
H	0.266	6.756
I	0.272	6.909
J	0.277	7.036
K	0.281	7.137
L	0.290	7.366
M	0.295	7.493
N	0.302	7.671
O	0.316	8.026
P	0.323	8.204
Q	0.332	8.433
R	0.339	8.611
S	0.348	8.839
T	0.358	9.093
U	0.368	9.347
V	0.377	9.576
W	0.386	9.804
X	0.397	10.084
Y	0.404	10.262
Z	0.413	10.490

Number Sizes

Number	Decimal (inches)	Metric (mm)
1	0.228	5.791
2	0.221	5.613
3	0.213	5.410
4	0.209	5.309
5	0.205	5.207
6	0.204	5.182
7	0.201	5.105
8	0.199	5.055
9	0.196	4.978
10	0.1935	4.915
11	0.191	4.851
12	0.189	4.801
13	0.185	4.699
14	0.182	4.623
15	0.180	4.572
16	0.177	4.496
17	0.173	4.394
18	0.1695	4.305
19	0.166	4.216
20	0.161	4.089
21	0.159	4.039
22	0.157	3.988
23	0.154	3.912
24	0.152	3.861
25	0.1495	3.797
26	0.147	3.734
27	0.144	3.658
28	0.1405	3.569
29	0.136	3.454
30	0.1285	3.264
31	0.120	3.048
32	0.116	2.946
33	0.113	2.870
34	0.111	2.819
35	0.110	2.794
36	0.1065	2.705
37	0.104	2.642
38	0.1015	2.578
39	0.0995	2.527
40	0.098	2.489
41	0.096	2.438
42	0.0935	2.375
43	0.089	2.261
44	0.086	2.184
45	0.082	2.083
46	0.081	2.057
47	0.0785	1.994
48	0.076	1.930
49	0.073	1.854
50	0.070	1.778
51	0.067	1.702
52	0.0635	1.613
53	0.0595	1.511
54	0.055	1.397
55	0.052	1.321
56	0.0465	1.181
57	0.043	1.092
58	0.042	1.067
59	0.041	1.041
60	0.040	1.016
61	0.039	0.991
62	0.038	0.965
63	0.037	0.940
64	0.036	0.914
65	0.035	0.889
66	0.033	0.838
67	0.032	0.813
68	0.031	0.787
69	0.0292	0.742
70	0.028	0.711
71	0.026	0.660
72	0.025	0.635
73	0.024	0.610
74	0.0225	0.572
75	0.021	0.533
76	0.020	0.508
77	0.018	0.457
78	0.016	0.406
79	0.0145	0.368
80	0.0135	0.343

Metric Sizes (Common)

Metric (mm)	Decimal (inches)
0.5	0.0197
1.0	0.0394
1.5	0.0591
2.0	0.0787
2.5	0.0984
3.0	0.1181
3.5	0.1378
4.0	0.1575
4.5	0.1772
5.0	0.1969
5.5	0.2165
6.0	0.2362
6.5	0.2559
7.0	0.2756
7.5	0.2953
8.0	0.3150
8.5	0.3346
9.0	0.3543
9.5	0.3740
10.0	0.3937
10.5	0.4134
11.0	0.4331
11.5	0.4528
12.0	0.4724
12.5	0.4921
13.0	0.5118
13.5	0.5315
14.0	0.5512
14.5	0.5709
15.0	0.5906
15.5	0.6102
16.0	0.6299
16.5	0.6496
17.0	0.6693
17.5	0.6890
18.0	0.7087
18.5	0.7283
19.0	0.7480
19.5	0.7677
20.0	0.7874

Find a large array of Drill Bits at MISUMI USA, and find more charts and articles at MISUMI’s Mech Lab Blog including a screw threads size chart.

Author: Scott Bredemann | Updated: 03/31/2025

Disclaimer
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers’ or manufacturers’ deliverables within MISUMI’s network. Buyers are responsible for specifying their part requirements