Drill Size Chart: Number, Letter, Fraction & Metric

A number drill runs from #80 (0.0135 in) up to #1 (0.2280 in), letter drills continue from A (0.2340 in) to Z (0.4130 in), and fractional drills step in 1/64 in. This chart puts all 381 sizes, plus common metric drills from 0.30 to 25 mm, in a single list sorted from smallest to largest.

Each row gives the drill name, its type, the decimal size in inches and the size in millimetres. The last column shows the nearest drill from the other system and how far off it is, so you can see at a glance whether a metric drill will stand in for an inch one. Type a size such as #29, 17/64 or 6.8 into the search box, filter by drill type, or enter any decimal under Nearest to to find the closest drill of each type.

Drill Size Chart: All Types by Size

Nearest to

Drill sizes sorted by diameter
Drill	Type	Inch (in)	Metric (mm)	Nearest other system
0.30 mm	Metric	0.0118	0.300	#80 0.0135 in, +0.0017 in
#80	Number	0.0135	0.343	0.35 mm +0.007 mm
0.35 mm	Metric	0.0138	0.350	#80 0.0135 in, -0.0003 in
#79	Number	0.0145	0.368	0.35 mm -0.018 mm
1/64"	Fraction	0.0156	0.397	0.4 mm +0.003 mm
0.40 mm	Metric	0.0157	0.400	1/64 0.0156 in, -0.0001 in
#78	Number	0.0160	0.406	0.4 mm -0.006 mm
0.45 mm	Metric	0.0177	0.450	#77 0.0180 in, +0.0003 in
#77	Number	0.0180	0.457	0.45 mm -0.007 mm
0.50 mm	Metric	0.0197	0.500	#76 0.0200 in, +0.0003 in
#76	Number	0.0200	0.508	0.5 mm -0.008 mm
#75	Number	0.0210	0.533	0.55 mm +0.017 mm
0.55 mm	Metric	0.0217	0.550	#75 0.0210 in, -0.0007 in
#74	Number	0.0225	0.571	0.55 mm -0.021 mm
0.60 mm	Metric	0.0236	0.600	#73 0.0240 in, +0.0004 in
#73	Number	0.0240	0.610	0.6 mm -0.010 mm
#72	Number	0.0250	0.635	0.65 mm +0.015 mm
0.65 mm	Metric	0.0256	0.650	#71 0.0260 in, +0.0004 in
#71	Number	0.0260	0.660	0.65 mm -0.010 mm
0.70 mm	Metric	0.0276	0.700	#70 0.0280 in, +0.0004 in
#70	Number	0.0280	0.711	0.7 mm -0.011 mm
#69	Number	0.0292	0.742	0.75 mm +0.008 mm
0.75 mm	Metric	0.0295	0.750	#69 0.0292 in, -0.0003 in
#68	Number	0.0310	0.787	0.8 mm +0.013 mm
1/32"	Fraction	0.0312	0.794	0.8 mm +0.006 mm
0.80 mm	Metric	0.0315	0.800	1/32 0.0312 in, -0.0002 in
#67	Number	0.0320	0.813	0.8 mm -0.013 mm
#66	Number	0.0330	0.838	0.85 mm +0.012 mm
0.85 mm	Metric	0.0335	0.850	#66 0.0330 in, -0.0005 in
#65	Number	0.0350	0.889	0.9 mm +0.011 mm
0.90 mm	Metric	0.0354	0.900	#65 0.0350 in, -0.0004 in
#64	Number	0.0360	0.914	0.9 mm -0.014 mm
#63	Number	0.0370	0.940	0.95 mm +0.010 mm
0.95 mm	Metric	0.0374	0.950	#63 0.0370 in, -0.0004 in
#62	Number	0.0380	0.965	0.95 mm -0.015 mm
#61	Number	0.0390	0.991	1 mm +0.009 mm
1.00 mm	Metric	0.0394	1.000	#61 0.0390 in, -0.0004 in
#60	Number	0.0400	1.016	1 mm -0.016 mm
#59	Number	0.0410	1.041	1.05 mm +0.009 mm
1.05 mm	Metric	0.0413	1.050	#59 0.0410 in, -0.0003 in
#58	Number	0.0420	1.067	1.05 mm -0.017 mm
#57	Number	0.0430	1.092	1.1 mm +0.008 mm
1.10 mm	Metric	0.0433	1.100	#57 0.0430 in, -0.0003 in
1.15 mm	Metric	0.0453	1.150	#56 0.0465 in, +0.0012 in
#56	Number	0.0465	1.181	1.2 mm +0.019 mm
3/64"	Fraction	0.0469	1.191	1.2 mm +0.009 mm
1.20 mm	Metric	0.0472	1.200	3/64 0.0469 in, -0.0004 in
1.25 mm	Metric	0.0492	1.250	3/64 0.0469 in, -0.0023 in
1.30 mm	Metric	0.0512	1.300	#55 0.0520 in, +0.0008 in
#55	Number	0.0520	1.321	1.3 mm -0.021 mm
1.35 mm	Metric	0.0531	1.350	#55 0.0520 in, -0.0011 in
#54	Number	0.0550	1.397	1.4 mm +0.003 mm
1.40 mm	Metric	0.0551	1.400	#54 0.0550 in, -0.0001 in
1.45 mm	Metric	0.0571	1.450	#54 0.0550 in, -0.0021 in
1.50 mm	Metric	0.0591	1.500	#53 0.0595 in, +0.0004 in
#53	Number	0.0595	1.511	1.5 mm -0.011 mm
1.55 mm	Metric	0.0610	1.550	1/16 0.0625 in, +0.0015 in
1/16"	Fraction	0.0625	1.587	1.6 mm +0.013 mm
1.60 mm	Metric	0.0630	1.600	1/16 0.0625 in, -0.0005 in
#52	Number	0.0635	1.613	1.6 mm -0.013 mm
1.65 mm	Metric	0.0650	1.650	#52 0.0635 in, -0.0015 in
1.70 mm	Metric	0.0669	1.700	#51 0.0670 in, +0.0001 in
#51	Number	0.0670	1.702	1.7 mm -0.002 mm
1.75 mm	Metric	0.0689	1.750	#50 0.0700 in, +0.0011 in
#50	Number	0.0700	1.778	1.8 mm +0.022 mm
1.80 mm	Metric	0.0709	1.800	#50 0.0700 in, -0.0009 in
1.85 mm	Metric	0.0728	1.850	#49 0.0730 in, +0.0002 in
#49	Number	0.0730	1.854	1.85 mm -0.004 mm
1.90 mm	Metric	0.0748	1.900	#48 0.0760 in, +0.0012 in
#48	Number	0.0760	1.930	1.95 mm +0.020 mm
1.95 mm	Metric	0.0768	1.950	#48 0.0760 in, -0.0008 in
5/64"	Fraction	0.0781	1.984	2 mm +0.016 mm
#47	Number	0.0785	1.994	2 mm +0.006 mm
2.00 mm	Metric	0.0787	2.000	#47 0.0785 in, -0.0002 in
2.05 mm	Metric	0.0807	2.050	#46 0.0810 in, +0.0003 in
#46	Number	0.0810	2.057	2.05 mm -0.007 mm
#45	Number	0.0820	2.083	2.1 mm +0.017 mm
2.10 mm	Metric	0.0827	2.100	#45 0.0820 in, -0.0007 in
2.15 mm	Metric	0.0846	2.150	#44 0.0860 in, +0.0014 in
#44	Number	0.0860	2.184	2.2 mm +0.016 mm
2.20 mm	Metric	0.0866	2.200	#44 0.0860 in, -0.0006 in
2.25 mm	Metric	0.0886	2.250	#43 0.0890 in, +0.0004 in
#43	Number	0.0890	2.261	2.25 mm -0.011 mm
2.30 mm	Metric	0.0906	2.300	#43 0.0890 in, -0.0016 in
2.35 mm	Metric	0.0925	2.350	#42 0.0935 in, +0.0010 in
#42	Number	0.0935	2.375	2.35 mm -0.025 mm
3/32"	Fraction	0.0938	2.381	2.4 mm +0.019 mm
2.40 mm	Metric	0.0945	2.400	3/32 0.0938 in, -0.0007 in
#41	Number	0.0960	2.438	2.45 mm +0.012 mm
2.45 mm	Metric	0.0965	2.450	#41 0.0960 in, -0.0005 in
#40	Number	0.0980	2.489	2.5 mm +0.011 mm
2.50 mm	Metric	0.0984	2.500	#40 0.0980 in, -0.0004 in
#39	Number	0.0995	2.527	2.55 mm +0.023 mm
2.55 mm	Metric	0.1004	2.550	#39 0.0995 in, -0.0009 in
#38	Number	0.1015	2.578	2.6 mm +0.022 mm
2.60 mm	Metric	0.1024	2.600	#38 0.1015 in, -0.0009 in
#37	Number	0.1040	2.642	2.65 mm +0.008 mm
2.65 mm	Metric	0.1043	2.650	#37 0.1040 in, -0.0003 in
2.70 mm	Metric	0.1063	2.700	#36 0.1065 in, +0.0002 in
#36	Number	0.1065	2.705	2.7 mm -0.005 mm
2.75 mm	Metric	0.1083	2.750	7/64 0.1094 in, +0.0011 in
7/64"	Fraction	0.1094	2.778	2.8 mm +0.022 mm
#35	Number	0.1100	2.794	2.8 mm +0.006 mm
2.80 mm	Metric	0.1102	2.800	#35 0.1100 in, -0.0002 in
#34	Number	0.1110	2.819	2.8 mm -0.019 mm
2.85 mm	Metric	0.1122	2.850	#33 0.1130 in, +0.0008 in
#33	Number	0.1130	2.870	2.85 mm -0.020 mm
2.90 mm	Metric	0.1142	2.900	#33 0.1130 in, -0.0012 in
#32	Number	0.1160	2.946	2.95 mm +0.004 mm
2.95 mm	Metric	0.1161	2.950	#32 0.1160 in, -0.0001 in
3.0 mm	Metric	0.1181	3.000	#31 0.1200 in, +0.0019 in
#31	Number	0.1200	3.048	3 mm -0.048 mm
3.1 mm	Metric	0.1220	3.100	#31 0.1200 in, -0.0020 in
1/8"	Fraction	0.1250	3.175	3.2 mm +0.025 mm
3.2 mm	Metric	0.1260	3.200	1/8 0.1250 in, -0.0010 in
#30	Number	0.1285	3.264	3.3 mm +0.036 mm
3.3 mm	Metric	0.1299	3.300	#30 0.1285 in, -0.0014 in
3.4 mm	Metric	0.1339	3.400	#29 0.1360 in, +0.0021 in
#29	Number	0.1360	3.454	3.5 mm +0.046 mm
3.5 mm	Metric	0.1378	3.500	#29 0.1360 in, -0.0018 in
#28	Number	0.1405	3.569	3.6 mm +0.031 mm
9/64"	Fraction	0.1406	3.572	3.6 mm +0.028 mm
3.6 mm	Metric	0.1417	3.600	9/64 0.1406 in, -0.0011 in
#27	Number	0.1440	3.658	3.7 mm +0.042 mm
3.7 mm	Metric	0.1457	3.700	#26 0.1470 in, +0.0013 in
#26	Number	0.1470	3.734	3.7 mm -0.034 mm
#25	Number	0.1495	3.797	3.8 mm +0.003 mm
3.8 mm	Metric	0.1496	3.800	#25 0.1495 in, -0.0001 in
#24	Number	0.1520	3.861	3.9 mm +0.039 mm
3.9 mm	Metric	0.1535	3.900	#23 0.1540 in, +0.0005 in
#23	Number	0.1540	3.912	3.9 mm -0.012 mm
5/32"	Fraction	0.1562	3.969	4 mm +0.031 mm
#22	Number	0.1570	3.988	4 mm +0.012 mm
4.0 mm	Metric	0.1575	4.000	#22 0.1570 in, -0.0005 in
#21	Number	0.1590	4.039	4 mm -0.039 mm
#20	Number	0.1610	4.089	4.1 mm +0.011 mm
4.1 mm	Metric	0.1614	4.100	#20 0.1610 in, -0.0004 in
4.2 mm	Metric	0.1654	4.200	#19 0.1660 in, +0.0006 in
#19	Number	0.1660	4.216	4.2 mm -0.016 mm
4.3 mm	Metric	0.1693	4.300	#18 0.1695 in, +0.0002 in
#18	Number	0.1695	4.305	4.3 mm -0.005 mm
11/64"	Fraction	0.1719	4.366	4.4 mm +0.034 mm
#17	Number	0.1730	4.394	4.4 mm +0.006 mm
4.4 mm	Metric	0.1732	4.400	#17 0.1730 in, -0.0002 in
#16	Number	0.1770	4.496	4.5 mm +0.004 mm
4.5 mm	Metric	0.1772	4.500	#16 0.1770 in, -0.0002 in
#15	Number	0.1800	4.572	4.6 mm +0.028 mm
4.6 mm	Metric	0.1811	4.600	#14 0.1820 in, +0.0009 in
#14	Number	0.1820	4.623	4.6 mm -0.023 mm
#13	Number	0.1850	4.699	4.7 mm +0.001 mm
4.7 mm	Metric	0.1850	4.700	#13 0.1850 in, -0.0000 in
3/16"	Fraction	0.1875	4.762	4.8 mm +0.038 mm
4.8 mm	Metric	0.1890	4.800	#12 0.1890 in, +0.0000 in
#12	Number	0.1890	4.801	4.8 mm -0.001 mm
#11	Number	0.1910	4.851	4.9 mm +0.049 mm
4.9 mm	Metric	0.1929	4.900	#10 0.1935 in, +0.0006 in
#10	Number	0.1935	4.915	4.9 mm -0.015 mm
#9	Number	0.1960	4.978	5 mm +0.022 mm
5.0 mm	Metric	0.1969	5.000	#9 0.1960 in, -0.0009 in
#8	Number	0.1990	5.055	5.1 mm +0.045 mm
5.1 mm	Metric	0.2008	5.100	#7 0.2010 in, +0.0002 in
#7	Number	0.2010	5.105	5.1 mm -0.005 mm
13/64"	Fraction	0.2031	5.159	5.2 mm +0.041 mm
#6	Number	0.2040	5.182	5.2 mm +0.018 mm
5.2 mm	Metric	0.2047	5.200	#6 0.2040 in, -0.0007 in
#5	Number	0.2055	5.220	5.2 mm -0.020 mm
5.3 mm	Metric	0.2087	5.300	#4 0.2090 in, +0.0003 in
#4	Number	0.2090	5.309	5.3 mm -0.009 mm
5.4 mm	Metric	0.2126	5.400	#3 0.2130 in, +0.0004 in
#3	Number	0.2130	5.410	5.4 mm -0.010 mm
5.5 mm	Metric	0.2165	5.500	7/32 0.2188 in, +0.0022 in
7/32"	Fraction	0.2188	5.556	5.6 mm +0.044 mm
5.6 mm	Metric	0.2205	5.600	#2 0.2210 in, +0.0005 in
#2	Number	0.2210	5.613	5.6 mm -0.013 mm
5.7 mm	Metric	0.2244	5.700	#2 0.2210 in, -0.0034 in
#1	Number	0.2280	5.791	5.8 mm +0.009 mm
5.8 mm	Metric	0.2283	5.800	#1 0.2280 in, -0.0003 in
5.9 mm	Metric	0.2323	5.900	A 0.2340 in, +0.0017 in
A	Letter	0.2340	5.944	5.9 mm -0.044 mm
15/64"	Fraction	0.2344	5.953	6 mm +0.047 mm
6.0 mm	Metric	0.2362	6.000	B 0.2380 in, +0.0018 in
B	Letter	0.2380	6.045	6 mm -0.045 mm
6.1 mm	Metric	0.2402	6.100	C 0.2420 in, +0.0018 in
C	Letter	0.2420	6.147	6.1 mm -0.047 mm
6.2 mm	Metric	0.2441	6.200	D 0.2460 in, +0.0019 in
D	Letter	0.2460	6.248	6.2 mm -0.048 mm
6.3 mm	Metric	0.2480	6.300	E 0.2500 in, +0.0020 in
E	Letter	0.2500	6.350	6.3 mm -0.050 mm
1/4"	Fraction	0.2500	6.350	6.3 mm -0.050 mm
6.4 mm	Metric	0.2520	6.400	E 0.2500 in, -0.0020 in
6.5 mm	Metric	0.2559	6.500	F 0.2570 in, +0.0011 in
F	Letter	0.2570	6.528	6.5 mm -0.028 mm
6.6 mm	Metric	0.2598	6.600	G 0.2610 in, +0.0012 in
G	Letter	0.2610	6.629	6.6 mm -0.029 mm
6.7 mm	Metric	0.2638	6.700	17/64 0.2656 in, +0.0018 in
17/64"	Fraction	0.2656	6.747	6.7 mm -0.047 mm
H	Letter	0.2660	6.756	6.8 mm +0.044 mm
6.8 mm	Metric	0.2677	6.800	H 0.2660 in, -0.0017 in
6.9 mm	Metric	0.2717	6.900	I 0.2720 in, +0.0003 in
I	Letter	0.2720	6.909	6.9 mm -0.009 mm
7.0 mm	Metric	0.2756	7.000	J 0.2770 in, +0.0014 in
J	Letter	0.2770	7.036	7 mm -0.036 mm
7.1 mm	Metric	0.2795	7.100	K 0.2810 in, +0.0015 in
K	Letter	0.2810	7.137	7.1 mm -0.037 mm
9/32"	Fraction	0.2812	7.144	7.1 mm -0.044 mm
7.2 mm	Metric	0.2835	7.200	9/32 0.2812 in, -0.0022 in
7.3 mm	Metric	0.2874	7.300	L 0.2900 in, +0.0026 in
L	Letter	0.2900	7.366	7.4 mm +0.034 mm
7.4 mm	Metric	0.2913	7.400	L 0.2900 in, -0.0013 in
M	Letter	0.2950	7.493	7.5 mm +0.007 mm
7.5 mm	Metric	0.2953	7.500	M 0.2950 in, -0.0003 in
19/64"	Fraction	0.2969	7.541	7.5 mm -0.041 mm
7.6 mm	Metric	0.2992	7.600	19/64 0.2969 in, -0.0023 in
N	Letter	0.3020	7.671	7.7 mm +0.029 mm
7.7 mm	Metric	0.3031	7.700	N 0.3020 in, -0.0011 in
7.8 mm	Metric	0.3071	7.800	N 0.3020 in, -0.0051 in
7.9 mm	Metric	0.3110	7.900	5/16 0.3125 in, +0.0015 in
5/16"	Fraction	0.3125	7.938	7.9 mm -0.037 mm
8.0 mm	Metric	0.3150	8.000	O 0.3160 in, +0.0010 in
O	Letter	0.3160	8.026	8 mm -0.026 mm
8.1 mm	Metric	0.3189	8.100	O 0.3160 in, -0.0029 in
8.2 mm	Metric	0.3228	8.200	P 0.3230 in, +0.0002 in
P	Letter	0.3230	8.204	8.2 mm -0.004 mm
8.3 mm	Metric	0.3268	8.300	21/64 0.3281 in, +0.0014 in
21/64"	Fraction	0.3281	8.334	8.3 mm -0.034 mm
8.4 mm	Metric	0.3307	8.400	Q 0.3320 in, +0.0013 in
Q	Letter	0.3320	8.433	8.4 mm -0.033 mm
8.5 mm	Metric	0.3346	8.500	Q 0.3320 in, -0.0026 in
8.6 mm	Metric	0.3386	8.600	R 0.3390 in, +0.0004 in
R	Letter	0.3390	8.611	8.6 mm -0.011 mm
8.7 mm	Metric	0.3425	8.700	11/32 0.3438 in, +0.0012 in
11/32"	Fraction	0.3438	8.731	8.7 mm -0.031 mm
8.8 mm	Metric	0.3465	8.800	S 0.3480 in, +0.0015 in
S	Letter	0.3480	8.839	8.8 mm -0.039 mm
8.9 mm	Metric	0.3504	8.900	S 0.3480 in, -0.0024 in
9.0 mm	Metric	0.3543	9.000	T 0.3580 in, +0.0037 in
T	Letter	0.3580	9.093	9.1 mm +0.007 mm
9.1 mm	Metric	0.3583	9.100	T 0.3580 in, -0.0003 in
23/64"	Fraction	0.3594	9.128	9.1 mm -0.028 mm
9.2 mm	Metric	0.3622	9.200	23/64 0.3594 in, -0.0028 in
9.3 mm	Metric	0.3661	9.300	U 0.3680 in, +0.0019 in
U	Letter	0.3680	9.347	9.3 mm -0.047 mm
9.4 mm	Metric	0.3701	9.400	U 0.3680 in, -0.0021 in
9.5 mm	Metric	0.3740	9.500	3/8 0.3750 in, +0.0010 in
3/8"	Fraction	0.3750	9.525	9.5 mm -0.025 mm
V	Letter	0.3770	9.576	9.6 mm +0.024 mm
9.6 mm	Metric	0.3780	9.600	V 0.3770 in, -0.0010 in
9.7 mm	Metric	0.3819	9.700	W 0.3860 in, +0.0041 in
9.8 mm	Metric	0.3858	9.800	W 0.3860 in, +0.0002 in
W	Letter	0.3860	9.804	9.8 mm -0.004 mm
9.9 mm	Metric	0.3898	9.900	25/64 0.3906 in, +0.0009 in
25/64"	Fraction	0.3906	9.922	9.9 mm -0.022 mm
10.0 mm	Metric	0.3937	10.000	25/64 0.3906 in, -0.0031 in
X	Letter	0.3970	10.084	10.1 mm +0.016 mm
10.1 mm	Metric	0.3976	10.100	X 0.3970 in, -0.0006 in
10.2 mm	Metric	0.4016	10.200	Y 0.4040 in, +0.0024 in
Y	Letter	0.4040	10.262	10.3 mm +0.038 mm
10.3 mm	Metric	0.4055	10.300	13/32 0.4062 in, +0.0007 in
13/32"	Fraction	0.4062	10.319	10.3 mm -0.019 mm
10.4 mm	Metric	0.4094	10.400	13/32 0.4062 in, -0.0032 in
Z	Letter	0.4130	10.490	10.5 mm +0.010 mm
10.5 mm	Metric	0.4134	10.500	Z 0.4130 in, -0.0004 in
10.6 mm	Metric	0.4173	10.600	Z 0.4130 in, -0.0043 in
10.7 mm	Metric	0.4213	10.700	27/64 0.4219 in, +0.0006 in
27/64"	Fraction	0.4219	10.716	10.7 mm -0.016 mm
10.8 mm	Metric	0.4252	10.800	27/64 0.4219 in, -0.0033 in
10.9 mm	Metric	0.4291	10.900	27/64 0.4219 in, -0.0073 in
11.0 mm	Metric	0.4331	11.000	7/16 0.4375 in, +0.0044 in
11.1 mm	Metric	0.4370	11.100	7/16 0.4375 in, +0.0005 in
7/16"	Fraction	0.4375	11.112	11.1 mm -0.012 mm
11.2 mm	Metric	0.4409	11.200	7/16 0.4375 in, -0.0034 in
11.3 mm	Metric	0.4449	11.300	7/16 0.4375 in, -0.0074 in
11.4 mm	Metric	0.4488	11.400	29/64 0.4531 in, +0.0043 in
11.5 mm	Metric	0.4528	11.500	29/64 0.4531 in, +0.0004 in
29/64"	Fraction	0.4531	11.509	11.5 mm -0.009 mm
11.6 mm	Metric	0.4567	11.600	29/64 0.4531 in, -0.0036 in
11.7 mm	Metric	0.4606	11.700	29/64 0.4531 in, -0.0075 in
11.8 mm	Metric	0.4646	11.800	15/32 0.4688 in, +0.0042 in
11.9 mm	Metric	0.4685	11.900	15/32 0.4688 in, +0.0002 in
15/32"	Fraction	0.4688	11.906	11.9 mm -0.006 mm
12.0 mm	Metric	0.4724	12.000	15/32 0.4688 in, -0.0037 in
12.1 mm	Metric	0.4764	12.100	15/32 0.4688 in, -0.0076 in
12.2 mm	Metric	0.4803	12.200	31/64 0.4844 in, +0.0041 in
12.3 mm	Metric	0.4843	12.300	31/64 0.4844 in, +0.0001 in
31/64"	Fraction	0.4844	12.303	12.3 mm -0.003 mm
12.4 mm	Metric	0.4882	12.400	31/64 0.4844 in, -0.0038 in
12.5 mm	Metric	0.4921	12.500	31/64 0.4844 in, -0.0078 in
12.6 mm	Metric	0.4961	12.600	1/2 0.5000 in, +0.0039 in
1/2"	Fraction	0.5000	12.700	12.7 mm +0.000 mm
12.7 mm	Metric	0.5000	12.700	1/2 0.5000 in, +0.0000 in
12.8 mm	Metric	0.5039	12.800	1/2 0.5000 in, -0.0039 in
12.9 mm	Metric	0.5079	12.900	33/64 0.5156 in, +0.0078 in
13.0 mm	Metric	0.5118	13.000	33/64 0.5156 in, +0.0038 in
33/64"	Fraction	0.5156	13.097	13 mm -0.097 mm
17/32"	Fraction	0.5312	13.494	13.5 mm +0.006 mm
13.5 mm	Metric	0.5315	13.500	17/32 0.5312 in, -0.0002 in
35/64"	Fraction	0.5469	13.891	14 mm +0.109 mm
14.0 mm	Metric	0.5512	14.000	35/64 0.5469 in, -0.0043 in
9/16"	Fraction	0.5625	14.287	14.5 mm +0.213 mm
14.5 mm	Metric	0.5709	14.500	37/64 0.5781 in, +0.0073 in
37/64"	Fraction	0.5781	14.684	14.5 mm -0.184 mm
15.0 mm	Metric	0.5906	15.000	19/32 0.5938 in, +0.0032 in
19/32"	Fraction	0.5938	15.081	15 mm -0.081 mm
39/64"	Fraction	0.6094	15.478	15.5 mm +0.022 mm
15.5 mm	Metric	0.6102	15.500	39/64 0.6094 in, -0.0009 in
5/8"	Fraction	0.6250	15.875	16 mm +0.125 mm
16.0 mm	Metric	0.6299	16.000	5/8 0.6250 in, -0.0049 in
41/64"	Fraction	0.6406	16.272	16.5 mm +0.228 mm
16.5 mm	Metric	0.6496	16.500	21/32 0.6562 in, +0.0066 in
21/32"	Fraction	0.6562	16.669	16.5 mm -0.169 mm
17.0 mm	Metric	0.6693	17.000	43/64 0.6719 in, +0.0026 in
43/64"	Fraction	0.6719	17.066	17 mm -0.066 mm
11/16"	Fraction	0.6875	17.462	17.5 mm +0.038 mm
17.5 mm	Metric	0.6890	17.500	11/16 0.6875 in, -0.0015 in
45/64"	Fraction	0.7031	17.859	18 mm +0.141 mm
18.0 mm	Metric	0.7087	18.000	45/64 0.7031 in, -0.0055 in
23/32"	Fraction	0.7188	18.256	18.5 mm +0.244 mm
18.5 mm	Metric	0.7283	18.500	47/64 0.7344 in, +0.0060 in
47/64"	Fraction	0.7344	18.653	18.5 mm -0.153 mm
19.0 mm	Metric	0.7480	19.000	3/4 0.7500 in, +0.0020 in
3/4"	Fraction	0.7500	19.050	19 mm -0.050 mm
49/64"	Fraction	0.7656	19.447	19.5 mm +0.053 mm
19.5 mm	Metric	0.7677	19.500	49/64 0.7656 in, -0.0021 in
25/32"	Fraction	0.7812	19.844	20 mm +0.156 mm
20.0 mm	Metric	0.7874	20.000	25/32 0.7812 in, -0.0062 in
51/64"	Fraction	0.7969	20.241	20 mm -0.241 mm
20.5 mm	Metric	0.8071	20.500	13/16 0.8125 in, +0.0054 in
13/16"	Fraction	0.8125	20.637	20.5 mm -0.137 mm
21.0 mm	Metric	0.8268	21.000	53/64 0.8281 in, +0.0014 in
53/64"	Fraction	0.8281	21.034	21 mm -0.034 mm
27/32"	Fraction	0.8438	21.431	21.5 mm +0.069 mm
21.5 mm	Metric	0.8465	21.500	27/32 0.8438 in, -0.0027 in
55/64"	Fraction	0.8594	21.828	22 mm +0.172 mm
22.0 mm	Metric	0.8661	22.000	55/64 0.8594 in, -0.0068 in
7/8"	Fraction	0.8750	22.225	22 mm -0.225 mm
22.5 mm	Metric	0.8858	22.500	57/64 0.8906 in, +0.0048 in
57/64"	Fraction	0.8906	22.622	22.5 mm -0.122 mm
23.0 mm	Metric	0.9055	23.000	29/32 0.9062 in, +0.0007 in
29/32"	Fraction	0.9062	23.019	23 mm -0.019 mm
59/64"	Fraction	0.9219	23.416	23.5 mm +0.084 mm
23.5 mm	Metric	0.9252	23.500	59/64 0.9219 in, -0.0033 in
15/16"	Fraction	0.9375	23.812	24 mm +0.188 mm
24.0 mm	Metric	0.9449	24.000	15/16 0.9375 in, -0.0074 in
61/64"	Fraction	0.9531	24.209	24 mm -0.209 mm
24.5 mm	Metric	0.9646	24.500	31/32 0.9688 in, +0.0042 in
31/32"	Fraction	0.9688	24.606	24.5 mm -0.106 mm
25.0 mm	Metric	0.9843	25.000	63/64 0.9844 in, +0.0001 in
63/64"	Fraction	0.9844	25.003	25 mm -0.003 mm
1"	Fraction	1.0000	25.400	25 mm -0.400 mm
1-1/64"	Fraction	1.0156	25.797	25 mm -0.797 mm
1-1/32"	Fraction	1.0312	26.194	25 mm -1.194 mm
1-3/64"	Fraction	1.0469	26.591	25 mm -1.591 mm
1-1/16"	Fraction	1.0625	26.987	25 mm -1.987 mm
1-5/64"	Fraction	1.0781	27.384	25 mm -2.384 mm
1-3/32"	Fraction	1.0938	27.781	25 mm -2.781 mm
1-7/64"	Fraction	1.1094	28.178	25 mm -3.178 mm
1-1/8"	Fraction	1.1250	28.575	25 mm -3.575 mm
1-9/64"	Fraction	1.1406	28.972	25 mm -3.972 mm
1-5/32"	Fraction	1.1562	29.369	25 mm -4.369 mm
1-11/64"	Fraction	1.1719	29.766	25 mm -4.766 mm
1-3/16"	Fraction	1.1875	30.162	25 mm -5.162 mm
1-13/64"	Fraction	1.2031	30.559	25 mm -5.559 mm
1-7/32"	Fraction	1.2188	30.956	25 mm -5.956 mm
1-15/64"	Fraction	1.2344	31.353	25 mm -6.353 mm
1-1/4"	Fraction	1.2500	31.750	25 mm -6.750 mm
1-17/64"	Fraction	1.2656	32.147	25 mm -7.147 mm
1-9/32"	Fraction	1.2812	32.544	25 mm -7.544 mm
1-19/64"	Fraction	1.2969	32.941	25 mm -7.941 mm
1-5/16"	Fraction	1.3125	33.337	25 mm -8.337 mm
1-21/64"	Fraction	1.3281	33.734	25 mm -8.734 mm
1-11/32"	Fraction	1.3438	34.131	25 mm -9.131 mm
1-23/64"	Fraction	1.3594	34.528	25 mm -9.528 mm
1-3/8"	Fraction	1.3750	34.925	25 mm -9.925 mm
1-25/64"	Fraction	1.3906	35.322	25 mm -10.322 mm
1-13/32"	Fraction	1.4062	35.719	25 mm -10.719 mm
1-27/64"	Fraction	1.4219	36.116	25 mm -11.116 mm
1-7/16"	Fraction	1.4375	36.512	25 mm -11.512 mm
1-29/64"	Fraction	1.4531	36.909	25 mm -11.909 mm
1-15/32"	Fraction	1.4688	37.306	25 mm -12.306 mm
1-31/64"	Fraction	1.4844	37.703	25 mm -12.703 mm
1-1/2"	Fraction	1.5000	38.100	25 mm -13.100 mm

80 number, 26 letter, 96 fractional and 179 metric drills. Decimal inch to 4 places, mm to 3 places.

How to Use This Drill Chart

Read across, not down. Because every type is merged into one list, the drills next to each other are the nearest sizes you can buy. For example, #3 (0.2130 in), 5.4 mm (0.2126 in) and 7/32 (0.2188 in) sit together.
Check the difference column. A positive number means the substitute drill is larger. For a clearance hole a few tenths over is fine; for a tap drill or a reamed hole, stay as close as possible.
Remember drills cut oversize. A sharp twist drill in a rigid machine typically cuts 0.001 to 0.003 in (0.02 to 0.08 mm) over its size; more if the point is ground unevenly. Ream or bore when the hole size matters.

Worked example: you need a 0.257 in hole for a 5/16-18 tap and only own metric drills. The chart shows letter F is 0.2570 in (6.528 mm); the nearest metric drill is 6.5 mm, which is 0.028 mm (0.0011 in) smaller. That is a perfectly good substitute and gives slightly more thread.

Shop tips

Use a drill gauge or micrometer across the margins to check unmarked drills; the shank is often slightly smaller than the cutting diameter.
Spot or centre drill first, and use a pilot drill for holes over about 1/2 in (13 mm) so the chisel edge does not wander.
For tap drills, use the Tap Drill Size Calculator or the thread size chart; for bolt holes, see the clearance hole chart.

Frequently Asked Questions

A #7 drill is 0.2010 in (5.105 mm). It is the standard tap drill for a 1/4-20 UNC thread, giving about 75% thread. The nearest metric drill is 5.1 mm.

An A drill is bigger. Number drills get larger as the number goes down, and #1 is 0.2280 in. Letter drills start just above that, with A at 0.2340 in, and get larger through Z at 0.4130 in.

A 1/4 in drill is exactly 6.35 mm. There is no 6.35 mm drill in the common metric series, so the closest metric drills are 6.3 mm (0.0020 in under) and 6.4 mm (0.0020 in over).

They fill the gaps between 1/64 in fractional steps. Number drills cover 0.0135 in to 0.2280 in and letter drills cover 0.2340 in to 0.4130 in, so you can pick a drill very close to an exact tap drill or clearance size.

Yes. Letter E is 0.2500 in, the same as a 1/4 in fractional drill. Most drill index sets include only one of the two.

Number and letter drill decimals are the nominal sizes from ASME B94.11M (twist drills). Fractional sizes are exact n/64 in values and all mm figures are inch × 25.4, rounded for display. Metric drills follow the common jobber series in 0.05, 0.1 and 0.5 mm steps; not every size is stocked by every supplier. Check critical sizes against the standard or the drill manufacturer's data.

Drill Size Chart: Number, Letter, Fractional and Metric

Drill Size Chart: All Types by Size

How to Use This Drill Chart

Shop tips

Frequently Asked Questions

What size is a #7 drill?

Which is bigger, a #1 drill or an A drill?

What is the metric equivalent of a 1/4 inch drill?

Why do number and letter drill sizes exist?

Is a letter E drill the same as 1/4 inch?

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