Drill Size Chart

Complete reference of Number, Letter, Fractional, and Metric drill sizes

Showing 256 of 256 drill sizes

Designation	Decimal (in)	Millimeters	Type
#80	0.0135	0.343	Number
#79	0.0145	0.368	Number
1/64	0.0156	0.396	Fractional
#78	0.0160	0.406	Number
#77	0.0180	0.457	Number
0.5mm	0.0197	0.500	Metric
#76	0.0200	0.508	Number
#75	0.0210	0.533	Number
#74	0.0225	0.571	Number
0.6mm	0.0236	0.600	Metric
#73	0.0240	0.610	Number
#72	0.0250	0.635	Number
#71	0.0260	0.660	Number
0.7mm	0.0276	0.700	Metric
#70	0.0280	0.711	Number
#69	0.0292	0.742	Number
#68	0.0310	0.787	Number
1/32	0.0313	0.795	Fractional
0.8mm	0.0315	0.800	Metric
#67	0.0320	0.813	Number
#66	0.0330	0.838	Number
#65	0.0350	0.889	Number
0.9mm	0.0354	0.900	Metric
#64	0.0360	0.914	Number
#63	0.0370	0.940	Number
#62	0.0380	0.965	Number
#61	0.0390	0.991	Number
1mm	0.0394	1.000	Metric
#60	0.0400	1.016	Number
#59	0.0410	1.041	Number
#58	0.0420	1.067	Number
#57	0.0430	1.092	Number
1.1mm	0.0433	1.100	Metric
#56	0.0465	1.181	Number
3/64	0.0469	1.191	Fractional
1.2mm	0.0472	1.200	Metric
1.3mm	0.0512	1.300	Metric
#55	0.0520	1.321	Number
#54	0.0550	1.397	Number
1.4mm	0.0551	1.400	Metric
1.5mm	0.0591	1.500	Metric
#53	0.0595	1.511	Number
1/16	0.0625	1.588	Fractional
1.6mm	0.0630	1.600	Metric
#52	0.0635	1.613	Number
1.7mm	0.0669	1.700	Metric
#51	0.0670	1.702	Number
#50	0.0700	1.778	Number
1.8mm	0.0709	1.800	Metric
#49	0.0730	1.854	Number
1.9mm	0.0748	1.900	Metric
#48	0.0760	1.930	Number
5/64	0.0781	1.984	Fractional
#47	0.0785	1.994	Number
2mm	0.0787	2.000	Metric
#46	0.0810	2.057	Number
#45	0.0820	2.083	Number
2.1mm	0.0827	2.100	Metric
#44	0.0860	2.184	Number
2.2mm	0.0866	2.200	Metric
#43	0.0890	2.261	Number
2.3mm	0.0906	2.300	Metric
#42	0.0935	2.375	Number
3/32	0.0938	2.383	Fractional
2.4mm	0.0945	2.400	Metric
#41	0.0960	2.438	Number
#40	0.0980	2.489	Number
2.5mm	0.0984	2.500	Metric
#39	0.0995	2.527	Number
#38	0.1015	2.578	Number
2.6mm	0.1024	2.600	Metric
#37	0.1040	2.642	Number
2.7mm	0.1063	2.700	Metric
#36	0.1065	2.705	Number
7/64	0.1094	2.779	Fractional
#35	0.1100	2.794	Number
2.8mm	0.1102	2.800	Metric
#34	0.1110	2.819	Number
#33	0.1130	2.870	Number
2.9mm	0.1142	2.900	Metric
#32	0.1160	2.946	Number
3mm	0.1181	3.000	Metric
#31	0.1200	3.048	Number
3.1mm	0.1220	3.100	Metric
1/8	0.1250	3.175	Fractional
3.2mm	0.1260	3.200	Metric
#30	0.1285	3.264	Number
3.3mm	0.1299	3.300	Metric
3.4mm	0.1339	3.400	Metric
#29	0.1360	3.454	Number
3.5mm	0.1378	3.500	Metric
#28	0.1405	3.569	Number
9/64	0.1406	3.571	Fractional
3.6mm	0.1417	3.600	Metric
#27	0.1440	3.658	Number
3.7mm	0.1457	3.700	Metric
#26	0.1470	3.734	Number
#25	0.1495	3.797	Number
3.8mm	0.1496	3.800	Metric
#24	0.1520	3.861	Number
3.9mm	0.1535	3.900	Metric
#23	0.1540	3.912	Number
5/32	0.1563	3.970	Fractional
#22	0.1570	3.988	Number
4mm	0.1575	4.000	Metric
#21	0.1590	4.039	Number
#20	0.1610	4.089	Number
4.1mm	0.1614	4.100	Metric
4.2mm	0.1654	4.200	Metric
#19	0.1660	4.216	Number
4.3mm	0.1693	4.300	Metric
#18	0.1695	4.305	Number
11/64	0.1719	4.366	Fractional
#17	0.1730	4.394	Number
4.4mm	0.1732	4.400	Metric
#16	0.1770	4.496	Number
4.5mm	0.1772	4.500	Metric
#15	0.1800	4.572	Number
4.6mm	0.1811	4.600	Metric
#14	0.1820	4.623	Number
#13	0.1850	4.699	Number
4.7mm	0.1850	4.700	Metric
3/16	0.1875	4.762	Fractional
#12	0.1890	4.801	Number
4.8mm	0.1890	4.800	Metric
#11	0.1910	4.851	Number
4.9mm	0.1929	4.900	Metric
#10	0.1935	4.915	Number
#9	0.1960	4.978	Number
5mm	0.1969	5.000	Metric
#8	0.1990	5.055	Number
#7	0.2010	5.105	Number
13/64	0.2031	5.159	Fractional
#6	0.2040	5.182	Number
#5	0.2055	5.220	Number
#4	0.2090	5.309	Number
#3	0.2130	5.410	Number
5.5mm	0.2165	5.500	Metric
7/32	0.2188	5.558	Fractional
#2	0.2210	5.613	Number
#1	0.2280	5.791	Number
A	0.2340	5.944	Letter
15/64	0.2344	5.954	Fractional
6mm	0.2362	6.000	Metric
B	0.2380	6.045	Letter
C	0.2420	6.147	Letter
D	0.2460	6.248	Letter
E	0.2500	6.350	Letter
1/4	0.2500	6.350	Fractional
6.5mm	0.2559	6.500	Metric
F	0.2570	6.528	Letter
G	0.2610	6.629	Letter
17/64	0.2656	6.746	Fractional
H	0.2660	6.756	Letter
I	0.2720	6.909	Letter
7mm	0.2756	7.000	Metric
J	0.2770	7.036	Letter
K	0.2810	7.137	Letter
9/32	0.2813	7.145	Fractional
L	0.2900	7.366	Letter
M	0.2950	7.493	Letter
7.5mm	0.2953	7.500	Metric
19/64	0.2969	7.541	Fractional
N	0.3020	7.671	Letter
5/16	0.3125	7.938	Fractional
8mm	0.3150	8.000	Metric
O	0.3160	8.026	Letter
P	0.3230	8.204	Letter
21/64	0.3281	8.334	Fractional
Q	0.3320	8.433	Letter
8.5mm	0.3346	8.500	Metric
R	0.3390	8.611	Letter
11/32	0.3438	8.733	Fractional
S	0.3480	8.839	Letter
9mm	0.3543	9.000	Metric
T	0.3580	9.093	Letter
23/64	0.3594	9.129	Fractional
U	0.3680	9.347	Letter
9.5mm	0.3740	9.500	Metric
3/8	0.3750	9.525	Fractional
V	0.3770	9.576	Letter
W	0.3860	9.804	Letter
25/64	0.3906	9.921	Fractional
10mm	0.3937	10.000	Metric
X	0.3970	10.084	Letter
Y	0.4040	10.262	Letter
13/32	0.4063	10.320	Fractional
Z	0.4130	10.490	Letter
10.5mm	0.4134	10.500	Metric
27/64	0.4219	10.716	Fractional
11mm	0.4331	11.000	Metric
7/16	0.4375	11.112	Fractional
11.5mm	0.4528	11.500	Metric
29/64	0.4531	11.509	Fractional
15/32	0.4688	11.908	Fractional
12mm	0.4724	12.000	Metric
31/64	0.4844	12.304	Fractional
12.5mm	0.4921	12.500	Metric
1/2	0.5000	12.700	Fractional
13mm	0.5118	13.000	Metric
33/64	0.5156	13.096	Fractional
17/32	0.5313	13.495	Fractional
13.5mm	0.5315	13.500	Metric
35/64	0.5469	13.891	Fractional
14mm	0.5512	14.000	Metric
9/16	0.5625	14.288	Fractional
14.5mm	0.5709	14.500	Metric
37/64	0.5781	14.684	Fractional
15mm	0.5906	15.000	Metric
19/32	0.5938	15.083	Fractional
39/64	0.6094	15.479	Fractional
15.5mm	0.6102	15.500	Metric
5/8	0.6250	15.875	Fractional
16mm	0.6299	16.000	Metric
41/64	0.6406	16.271	Fractional
16.5mm	0.6496	16.500	Metric
21/32	0.6563	16.670	Fractional
17mm	0.6693	17.000	Metric
43/64	0.6719	17.066	Fractional
11/16	0.6875	17.463	Fractional
17.5mm	0.6890	17.500	Metric
45/64	0.7031	17.859	Fractional
18mm	0.7087	18.000	Metric
23/32	0.7188	18.258	Fractional
18.5mm	0.7283	18.500	Metric
47/64	0.7344	18.654	Fractional
19mm	0.7480	19.000	Metric
3/4	0.7500	19.050	Fractional
49/64	0.7656	19.446	Fractional
19.5mm	0.7677	19.500	Metric
25/32	0.7813	19.845	Fractional
20mm	0.7874	20.000	Metric
51/64	0.7969	20.241	Fractional
20.5mm	0.8071	20.500	Metric
13/16	0.8125	20.638	Fractional
21mm	0.8268	21.000	Metric
53/64	0.8281	21.034	Fractional
27/32	0.8438	21.433	Fractional
21.5mm	0.8465	21.500	Metric
55/64	0.8594	21.829	Fractional
22mm	0.8661	22.000	Metric
7/8	0.8750	22.225	Fractional
22.5mm	0.8858	22.500	Metric
57/64	0.8906	22.621	Fractional
23mm	0.9055	23.000	Metric
29/32	0.9063	23.020	Fractional
59/64	0.9219	23.416	Fractional
23.5mm	0.9252	23.500	Metric
15/16	0.9375	23.813	Fractional
24mm	0.9449	24.000	Metric
61/64	0.9531	24.209	Fractional
24.5mm	0.9646	24.500	Metric
31/32	0.9688	24.608	Fractional
25mm	0.9843	25.000	Metric
63/64	0.9844	25.004	Fractional
1	1.0000	25.400	Fractional

Understanding Drill Size Systems

Machinists work with four different drill sizing systems. Each one evolved to fill gaps left by the others, and knowing how to cross-reference between them is essential for finding the right drill for any job.

Number Drills (#1 – #80)

Number drills follow the wire gauge standard. The numbering is counterintuitive: #80 is the smallest (0.0135") and #1 is the largest (0.2280"). These drills fill the fine gaps between fractional sizes and are commonly specified as tap drills for smaller thread sizes.

Letter Drills (A – Z)

Letter drills pick up where number drills leave off. Starting at A (0.234") and ending at Z (0.413"), they fill the gaps between fractional sizes in the mid-range. Letter drills are frequently specified for clearance holes and tap drills for larger thread sizes.

Fractional Drills

Fractional drills are the most familiar system, sized in increments of 1/64". They range from 1/64" (0.0156") to well over 1", though this chart covers the most common range up to 1". These are the workhorses of general-purpose drilling.

Metric Drills

Metric drills are sized in millimeters and follow ISO standards. They're essential for metric fastener work and international projects. Common sizes range from 0.5mm to 25mm, with finer increments (0.1mm) in smaller sizes and larger steps (0.5–1mm) above 5mm.

How to Use This Chart

Use the filter buttons to show or hide drill types, or type in the search box to find a specific size. All drills are sorted by diameter from smallest to largest, making it easy to find alternatives when you don't have the exact size called out on a print. Click a type filter to quickly compare sizes within one system.