Drill Size Chart

Type #7, F, 5/16, 0.201, 6.5 mm, or a thread such as M6 or 1/4-20; results appear as you type. The full chart below can be filtered and downloaded as CSV.

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Results

Drill series explained

Size ranges of the four drill series

Number drills run from #1 down to #80 (#97 smallest); letter drills A–Z continue above #1; fractional sizes step by 1/64"; metric sizes step by 0.05–0.1 mm.

How a drill size is measured

The size is the diameter across the margins, measured with a micrometer just behind the point; for example a #7 drill (0.2010") is the tap drill for 1/4-20 UNC.

Complete drill size chart (491 sizes)

All four series merged in size order. Filter by #, letter, fraction, mm or thread (e.g. M8).

Filter chart

Complete drill size chart (491 sizes)
Size	Series	in	mm	Tap drill for
0.05 mm	Metric	0.00197	0.05	—
0.1 mm	Metric	0.00394	0.1	—
#97	Number (#)	0.0059	0.1499	—
0.15 mm	Metric	0.00591	0.15	—
#96	Number (#)	0.0063	0.16	—
#95	Number (#)	0.0067	0.1702	—
#94	Number (#)	0.0071	0.1803	—
#93	Number (#)	0.0075	0.1905	—
0.2 mm	Metric	0.00787	0.2	—
#92	Number (#)	0.0079	0.2007	—
#91	Number (#)	0.0083	0.2108	—
#90	Number (#)	0.0087	0.221	—
#89	Number (#)	0.0091	0.2311	—
#88	Number (#)	0.0095	0.2413	—
0.25 mm	Metric	0.00984	0.25	—
#87	Number (#)	0.01	0.254	—
#86	Number (#)	0.0105	0.2667	—
#85	Number (#)	0.011	0.2794	—
#84	Number (#)	0.0115	0.2921	—
0.3 mm	Metric	0.01181	0.3	—
#83	Number (#)	0.012	0.3048	—
#82	Number (#)	0.0125	0.3175	—
#81	Number (#)	0.013	0.3302	—
#80	Number (#)	0.0135	0.3429	—
0.35 mm	Metric	0.01378	0.35	—
#79	Number (#)	0.0145	0.3683	—
1/64"	Fractional inch	0.01562	0.3969	—
0.4 mm	Metric	0.01575	0.4	—
#78	Number (#)	0.016	0.4064	—
0.45 mm	Metric	0.01772	0.45	—
#77	Number (#)	0.018	0.4572	—
0.5 mm	Metric	0.01969	0.5	—
#76	Number (#)	0.02	0.508	—
#75	Number (#)	0.021	0.5334	—
0.55 mm	Metric	0.02165	0.55	—
#74	Number (#)	0.0225	0.5715	—
0.6 mm	Metric	0.02362	0.6	—
#73	Number (#)	0.024	0.6096	—
#72	Number (#)	0.025	0.635	—
0.65 mm	Metric	0.02559	0.65	—
#71	Number (#)	0.026	0.6604	—
0.7 mm	Metric	0.02756	0.7	—
#70	Number (#)	0.028	0.7112	—
#69	Number (#)	0.0292	0.7417	—
0.75 mm	Metric	0.02953	0.75	—
#68	Number (#)	0.031	0.7874	—
1/32"	Fractional inch	0.03125	0.7937	—
0.8 mm	Metric	0.0315	0.8	—
#67	Number (#)	0.032	0.8128	—
#66	Number (#)	0.033	0.8382	—
0.85 mm	Metric	0.03346	0.85	—
#65	Number (#)	0.035	0.889	—
0.9 mm	Metric	0.03543	0.9	—
#64	Number (#)	0.036	0.9144	—
#63	Number (#)	0.037	0.9398	—
0.95 mm	Metric	0.0374	0.95	—
#62	Number (#)	0.038	0.9652	—
#61	Number (#)	0.039	0.9906	—
1 mm	Metric	0.03937	1	—
#60	Number (#)	0.04	1.016	—
#59	Number (#)	0.041	1.0414	—
1.05 mm	Metric	0.04134	1.05	—
#58	Number (#)	0.042	1.0668	—
#57	Number (#)	0.043	1.0922	—
1.1 mm	Metric	0.04331	1.1	—
1.15 mm	Metric	0.04528	1.15	—
#56	Number (#)	0.0465	1.1811	—
3/64"	Fractional inch	0.04688	1.1906	—
1.2 mm	Metric	0.04724	1.2	—
1.25 mm	Metric	0.04921	1.25	—
1.3 mm	Metric	0.05118	1.3	—
#55	Number (#)	0.052	1.3208	—
1.35 mm	Metric	0.05315	1.35	—
#54	Number (#)	0.055	1.397	—
1.4 mm	Metric	0.05512	1.4	—
1.45 mm	Metric	0.05709	1.45	—
1.5 mm	Metric	0.05906	1.5	—
#53	Number (#)	0.0595	1.5113	—
1.55 mm	Metric	0.06102	1.55	#1-64 UNC, #1-72 UNF
1/16"	Fractional inch	0.0625	1.5875	—
1.6 mm	Metric	0.06299	1.6	—
#52	Number (#)	0.0635	1.6129	—
1.65 mm	Metric	0.06496	1.65	—
1.7 mm	Metric	0.06693	1.7	—
#51	Number (#)	0.067	1.7018	—
1.75 mm	Metric	0.0689	1.75	—
#50	Number (#)	0.07	1.778	—
1.8 mm	Metric	0.07087	1.8	—
1.85 mm	Metric	0.07283	1.85	#2-56 UNC, #2-64 UNF
#49	Number (#)	0.073	1.8542	#2-56 UNC, #2-64 UNF
1.9 mm	Metric	0.0748	1.9	—
#48	Number (#)	0.076	1.9304	—
1.95 mm	Metric	0.07677	1.95	—
5/64"	Fractional inch	0.07812	1.9844	—
#47	Number (#)	0.0785	1.9939	—
2 mm	Metric	0.07874	2	—
2.05 mm	Metric	0.08071	2.05	—
#46	Number (#)	0.081	2.0574	—
#45	Number (#)	0.082	2.0828	—
2.1 mm	Metric	0.08268	2.1	—
2.15 mm	Metric	0.08465	2.15	—
#44	Number (#)	0.086	2.1844	—
2.2 mm	Metric	0.08661	2.2	—
2.25 mm	Metric	0.08858	2.25	—
#43	Number (#)	0.089	2.2606	—
2.3 mm	Metric	0.09055	2.3	—
2.35 mm	Metric	0.09252	2.35	#4-40 UNC
#42	Number (#)	0.0935	2.3749	—
3/32"	Fractional inch	0.09375	2.3812	—
2.4 mm	Metric	0.09449	2.4	#4-48 UNF
#41	Number (#)	0.096	2.4384	—
2.45 mm	Metric	0.09646	2.45	—
#40	Number (#)	0.098	2.4892	—
2.5 mm	Metric	0.09843	2.5	M3 × 0.5
#39	Number (#)	0.0995	2.5273	—
2.55 mm	Metric	0.10039	2.55	—
#38	Number (#)	0.1015	2.5781	—
2.6 mm	Metric	0.10236	2.6	—
#37	Number (#)	0.104	2.6416	—
2.65 mm	Metric	0.10433	2.65	M3 × 0.35
2.7 mm	Metric	0.1063	2.7	—
#36	Number (#)	0.1065	2.7051	—
2.75 mm	Metric	0.10827	2.75	—
7/64"	Fractional inch	0.10938	2.7781	—
#35	Number (#)	0.11	2.794	—
2.8 mm	Metric	0.11024	2.8	—
#34	Number (#)	0.111	2.8194	—
2.85 mm	Metric	0.1122	2.85	#6-32 UNC
#33	Number (#)	0.113	2.8702	—
2.9 mm	Metric	0.11417	2.9	—
#32	Number (#)	0.116	2.9464	#6-40 UNF
2.95 mm	Metric	0.11614	2.95	#6-40 UNF
3 mm	Metric	0.11811	3	—
#31	Number (#)	0.12	3.048	—
3.05 mm	Metric	0.12008	3.05	—
3.1 mm	Metric	0.12205	3.1	—
3.15 mm	Metric	0.12402	3.15	—
1/8"	Fractional inch	0.125	3.175	—
3.2 mm	Metric	0.12598	3.2	—
3.25 mm	Metric	0.12795	3.25	—
#30	Number (#)	0.1285	3.2639	—
3.3 mm	Metric	0.12992	3.3	M4 × 0.7
3.35 mm	Metric	0.13189	3.35	—
3.4 mm	Metric	0.13386	3.4	—
3.45 mm	Metric	0.13583	3.45	—
#29	Number (#)	0.136	3.4544	—
3.5 mm	Metric	0.1378	3.5	M4 × 0.5, #8-32 UNC, #8-36 UNF
3.55 mm	Metric	0.13976	3.55	—
#28	Number (#)	0.1405	3.5687	—
9/64"	Fractional inch	0.14062	3.5719	—
3.6 mm	Metric	0.14173	3.6	—
3.65 mm	Metric	0.1437	3.65	—
#27	Number (#)	0.144	3.6576	—
3.7 mm	Metric	0.14567	3.7	—
#26	Number (#)	0.147	3.7338	—
3.75 mm	Metric	0.14764	3.75	—
#25	Number (#)	0.1495	3.7973	—
3.8 mm	Metric	0.14961	3.8	—
3.85 mm	Metric	0.15157	3.85	—
#24	Number (#)	0.152	3.8608	—
3.9 mm	Metric	0.15354	3.9	#10-24 UNC
#23	Number (#)	0.154	3.9116	—
3.95 mm	Metric	0.15551	3.95	—
5/32"	Fractional inch	0.15625	3.9688	—
#22	Number (#)	0.157	3.9878	—
4 mm	Metric	0.15748	4	—
#21	Number (#)	0.159	4.0386	—
4.05 mm	Metric	0.15945	4.05	—
#20	Number (#)	0.161	4.0894	—
4.1 mm	Metric	0.16142	4.1	#10-32 UNF
4.15 mm	Metric	0.16339	4.15	—
4.2 mm	Metric	0.16535	4.2	M5 × 0.8
#19	Number (#)	0.166	4.2164	—
4.25 mm	Metric	0.16732	4.25	—
4.3 mm	Metric	0.16929	4.3	—
#18	Number (#)	0.1695	4.3053	—
4.35 mm	Metric	0.17126	4.35	—
11/64"	Fractional inch	0.17188	4.3656	—
#17	Number (#)	0.173	4.3942	—
4.4 mm	Metric	0.17323	4.4	—
4.45 mm	Metric	0.1752	4.45	—
#16	Number (#)	0.177	4.4958	M5 × 0.5, #12-24 UNC
4.5 mm	Metric	0.17717	4.5	M5 × 0.5, #12-24 UNC
4.55 mm	Metric	0.17913	4.55	—
#15	Number (#)	0.18	4.572	—
4.6 mm	Metric	0.1811	4.6	#12-28 UNF
#14	Number (#)	0.182	4.6228	—
4.65 mm	Metric	0.18307	4.65	—
#13	Number (#)	0.185	4.699	—
4.7 mm	Metric	0.18504	4.7	—
4.75 mm	Metric	0.18701	4.75	—
3/16"	Fractional inch	0.1875	4.7625	—
4.8 mm	Metric	0.18898	4.8	—
#12	Number (#)	0.189	4.8006	—
4.85 mm	Metric	0.19094	4.85	—
#11	Number (#)	0.191	4.8514	—
4.9 mm	Metric	0.19291	4.9	—
#10	Number (#)	0.1935	4.9149	—
4.95 mm	Metric	0.19488	4.95	—
#9	Number (#)	0.196	4.9784	—
5 mm	Metric	0.19685	5	M6 × 1
#8	Number (#)	0.199	5.0546	—
5.1 mm	Metric	0.20079	5.1	1/4-20 UNC
#7	Number (#)	0.201	5.1054	1/4-20 UNC
13/64"	Fractional inch	0.20312	5.1594	—
#6	Number (#)	0.204	5.1816	—
5.2 mm	Metric	0.20472	5.2	M6 × 0.75
#5	Number (#)	0.2055	5.2197	—
5.3 mm	Metric	0.20866	5.3	—
#4	Number (#)	0.209	5.3086	—
5.4 mm	Metric	0.2126	5.4	—
#3	Number (#)	0.213	5.4102	—
5.5 mm	Metric	0.21654	5.5	1/4-28 UNF
7/32"	Fractional inch	0.21875	5.5562	—
5.6 mm	Metric	0.22047	5.6	—
#2	Number (#)	0.221	5.6134	—
5.7 mm	Metric	0.22441	5.7	—
#1	Number (#)	0.228	5.7912	—
5.8 mm	Metric	0.22835	5.8	—
5.9 mm	Metric	0.23228	5.9	—
A	Letter	0.234	5.9436	—
15/64"	Fractional inch	0.23438	5.9531	—
6 mm	Metric	0.23622	6	—
B	Letter	0.238	6.0452	—
6.1 mm	Metric	0.24016	6.1	—
C	Letter	0.242	6.1468	—
6.2 mm	Metric	0.24409	6.2	—
D	Letter	0.246	6.2484	—
6.3 mm	Metric	0.24803	6.3	—
1/4"	Fractional inch	0.25	6.35	—
E	Letter	0.25	6.35	—
6.4 mm	Metric	0.25197	6.4	—
6.5 mm	Metric	0.25591	6.5	—
F	Letter	0.257	6.5278	—
6.6 mm	Metric	0.25984	6.6	5/16-18 UNC
G	Letter	0.261	6.6294	—
6.7 mm	Metric	0.26378	6.7	—
17/64"	Fractional inch	0.26562	6.7469	—
H	Letter	0.266	6.7564	—
6.8 mm	Metric	0.26772	6.8	M8 × 1.25
6.9 mm	Metric	0.27165	6.9	5/16-24 UNF
I	Letter	0.272	6.9088	—
7 mm	Metric	0.27559	7	M8 × 1
J	Letter	0.277	7.0358	—
7.1 mm	Metric	0.27953	7.1	—
K	Letter	0.281	7.1374	—
9/32"	Fractional inch	0.28125	7.1437	—
7.2 mm	Metric	0.28346	7.2	M8 × 0.75
7.3 mm	Metric	0.2874	7.3	—
L	Letter	0.29	7.366	—
7.4 mm	Metric	0.29134	7.4	—
M	Letter	0.295	7.493	—
7.5 mm	Metric	0.29528	7.5	—
19/64"	Fractional inch	0.29688	7.5406	—
7.6 mm	Metric	0.29921	7.6	—
N	Letter	0.302	7.6708	—
7.7 mm	Metric	0.30315	7.7	—
7.8 mm	Metric	0.30709	7.8	—
7.9 mm	Metric	0.31102	7.9	—
5/16"	Fractional inch	0.3125	7.9375	—
8 mm	Metric	0.31496	8	3/8-16 UNC
O	Letter	0.316	8.0264	—
8.1 mm	Metric	0.3189	8.1	—
8.2 mm	Metric	0.32283	8.2	—
P	Letter	0.323	8.2042	—
8.3 mm	Metric	0.32677	8.3	—
21/64"	Fractional inch	0.32812	8.3344	—
8.4 mm	Metric	0.33071	8.4	—
Q	Letter	0.332	8.4328	—
8.5 mm	Metric	0.33465	8.5	M10 × 1.5, 3/8-24 UNF
8.6 mm	Metric	0.33858	8.6	—
R	Letter	0.339	8.6106	—
8.7 mm	Metric	0.34252	8.7	—
11/32"	Fractional inch	0.34375	8.7312	—
8.8 mm	Metric	0.34646	8.8	M10 × 1.25
S	Letter	0.348	8.8392	—
8.9 mm	Metric	0.35039	8.9	—
9 mm	Metric	0.35433	9	M10 × 1
T	Letter	0.358	9.0932	—
9.1 mm	Metric	0.35827	9.1	—
23/64"	Fractional inch	0.35938	9.1281	—
9.2 mm	Metric	0.3622	9.2	M10 × 0.75
9.3 mm	Metric	0.36614	9.3	—
U	Letter	0.368	9.3472	—
9.4 mm	Metric	0.37008	9.4	7/16-14 UNC
9.5 mm	Metric	0.37402	9.5	—
3/8"	Fractional inch	0.375	9.525	—
V	Letter	0.377	9.5758	—
9.6 mm	Metric	0.37795	9.6	—
9.7 mm	Metric	0.38189	9.7	—
9.8 mm	Metric	0.38583	9.8	—
W	Letter	0.386	9.8044	—
9.9 mm	Metric	0.38976	9.9	7/16-20 UNF
25/64"	Fractional inch	0.39062	9.9219	—
10 mm	Metric	0.3937	10	—
X	Letter	0.397	10.0838	—
10.1 mm	Metric	0.39764	10.1	—
10.2 mm	Metric	0.40157	10.2	M12 × 1.75
Y	Letter	0.404	10.2616	—
10.3 mm	Metric	0.40551	10.3	—
13/32"	Fractional inch	0.40625	10.3187	—
10.4 mm	Metric	0.40945	10.4	—
Z	Letter	0.413	10.4902	—
10.5 mm	Metric	0.41339	10.5	M12 × 1.5
10.6 mm	Metric	0.41732	10.6	—
10.7 mm	Metric	0.42126	10.7	—
27/64"	Fractional inch	0.42188	10.7156	—
10.8 mm	Metric	0.4252	10.8	M12 × 1.25, 1/2-13 UNC
10.9 mm	Metric	0.42913	10.9	—
11 mm	Metric	0.43307	11	M12 × 1
11.1 mm	Metric	0.43701	11.1	—
7/16"	Fractional inch	0.4375	11.1125	—
11.2 mm	Metric	0.44094	11.2	—
11.3 mm	Metric	0.44488	11.3	—
11.4 mm	Metric	0.44882	11.4	—
11.5 mm	Metric	0.45276	11.5	1/2-20 UNF
29/64"	Fractional inch	0.45312	11.5094	—
11.6 mm	Metric	0.45669	11.6	—
11.7 mm	Metric	0.46063	11.7	—
11.8 mm	Metric	0.46457	11.8	—
11.9 mm	Metric	0.4685	11.9	—
15/32"	Fractional inch	0.46875	11.9062	—
12 mm	Metric	0.47244	12	M14 × 2
12.1 mm	Metric	0.47638	12.1	—
12.2 mm	Metric	0.48031	12.2	9/16-12 UNC
12.3 mm	Metric	0.48425	12.3	—
31/64"	Fractional inch	0.48438	12.3031	—
12.4 mm	Metric	0.48819	12.4	—
12.5 mm	Metric	0.49213	12.5	M14 × 1.5
12.6 mm	Metric	0.49606	12.6	—
1/2"	Fractional inch	0.5	12.7	—
12.7 mm	Metric	0.5	12.7	—
12.8 mm	Metric	0.50394	12.8	—
12.9 mm	Metric	0.50787	12.9	9/16-18 UNF
13 mm	Metric	0.51181	13	—
33/64"	Fractional inch	0.51562	13.0969	—
13.1 mm	Metric	0.51575	13.1	—
13.2 mm	Metric	0.51969	13.2	—
13.3 mm	Metric	0.52362	13.3	—
13.4 mm	Metric	0.52756	13.4	—
17/32"	Fractional inch	0.53125	13.4937	—
13.5 mm	Metric	0.5315	13.5	5/8-11 UNC
13.6 mm	Metric	0.53543	13.6	—
13.7 mm	Metric	0.53937	13.7	—
13.8 mm	Metric	0.54331	13.8	—
35/64"	Fractional inch	0.54688	13.8906	—
13.9 mm	Metric	0.54724	13.9	—
14 mm	Metric	0.55118	14	M16 × 2
14.1 mm	Metric	0.55512	14.1	—
14.2 mm	Metric	0.55906	14.2	—
9/16"	Fractional inch	0.5625	14.2875	—
14.3 mm	Metric	0.56299	14.3	—
14.4 mm	Metric	0.56693	14.4	—
14.5 mm	Metric	0.57087	14.5	M16 × 1.5, 5/8-18 UNF
14.6 mm	Metric	0.5748	14.6	—
37/64"	Fractional inch	0.57812	14.6844	—
14.7 mm	Metric	0.57874	14.7	—
14.8 mm	Metric	0.58268	14.8	—
14.9 mm	Metric	0.58661	14.9	—
15 mm	Metric	0.59055	15	M16 × 1
19/32"	Fractional inch	0.59375	15.0812	—
15.1 mm	Metric	0.59449	15.1	—
15.2 mm	Metric	0.59843	15.2	—
15.3 mm	Metric	0.60236	15.3	—
15.4 mm	Metric	0.6063	15.4	—
39/64"	Fractional inch	0.60938	15.4781	—
15.5 mm	Metric	0.61024	15.5	M18 × 2.5
15.6 mm	Metric	0.61417	15.6	—
15.7 mm	Metric	0.61811	15.7	—
15.8 mm	Metric	0.62205	15.8	—
5/8"	Fractional inch	0.625	15.875	—
15.9 mm	Metric	0.62598	15.9	—
16 mm	Metric	0.62992	16	—
16.1 mm	Metric	0.63386	16.1	—
16.2 mm	Metric	0.6378	16.2	—
41/64"	Fractional inch	0.64062	16.2719	—
16.3 mm	Metric	0.64173	16.3	—
16.4 mm	Metric	0.64567	16.4	—
16.5 mm	Metric	0.64961	16.5	M18 × 1.5, 3/4-10 UNC
16.6 mm	Metric	0.65354	16.6	—
21/32"	Fractional inch	0.65625	16.6687	—
16.7 mm	Metric	0.65748	16.7	—
16.8 mm	Metric	0.66142	16.8	—
16.9 mm	Metric	0.66535	16.9	—
17 mm	Metric	0.66929	17	—
43/64"	Fractional inch	0.67188	17.0656	—
17.1 mm	Metric	0.67323	17.1	—
17.2 mm	Metric	0.67717	17.2	—
17.3 mm	Metric	0.6811	17.3	—
17.4 mm	Metric	0.68504	17.4	—
11/16"	Fractional inch	0.6875	17.4625	—
17.5 mm	Metric	0.68898	17.5	M20 × 2.5, 3/4-16 UNF
17.6 mm	Metric	0.69291	17.6	—
17.7 mm	Metric	0.69685	17.7	—
17.8 mm	Metric	0.70079	17.8	—
45/64"	Fractional inch	0.70312	17.8594	—
17.9 mm	Metric	0.70472	17.9	—
18 mm	Metric	0.70866	18	—
18.1 mm	Metric	0.7126	18.1	—
18.2 mm	Metric	0.71654	18.2	—
23/32"	Fractional inch	0.71875	18.2562	—
18.3 mm	Metric	0.72047	18.3	—
18.4 mm	Metric	0.72441	18.4	—
18.5 mm	Metric	0.72835	18.5	M20 × 1.5
18.6 mm	Metric	0.73228	18.6	—
47/64"	Fractional inch	0.73438	18.6531	—
18.7 mm	Metric	0.73622	18.7	—
18.8 mm	Metric	0.74016	18.8	—
18.9 mm	Metric	0.74409	18.9	—
19 mm	Metric	0.74803	19	—
3/4"	Fractional inch	0.75	19.05	—
19.1 mm	Metric	0.75197	19.1	—
19.2 mm	Metric	0.75591	19.2	—
19.3 mm	Metric	0.75984	19.3	—
19.4 mm	Metric	0.76378	19.4	—
49/64"	Fractional inch	0.76562	19.4469	—
19.5 mm	Metric	0.76772	19.5	M22 × 2.5, 7/8-9 UNC
19.6 mm	Metric	0.77165	19.6	—
19.7 mm	Metric	0.77559	19.7	—
19.8 mm	Metric	0.77953	19.8	—
25/32"	Fractional inch	0.78125	19.8438	—
19.9 mm	Metric	0.78346	19.9	—
20 mm	Metric	0.7874	20	—
20.1 mm	Metric	0.79134	20.1	—
20.2 mm	Metric	0.79528	20.2	—
51/64"	Fractional inch	0.79688	20.2406	—
20.3 mm	Metric	0.79921	20.3	—
20.4 mm	Metric	0.80315	20.4	7/8-14 UNF
20.5 mm	Metric	0.80709	20.5	—
20.6 mm	Metric	0.81102	20.6	—
13/16"	Fractional inch	0.8125	20.6375	—
20.7 mm	Metric	0.81496	20.7	—
20.8 mm	Metric	0.8189	20.8	—
20.9 mm	Metric	0.82283	20.9	—
21 mm	Metric	0.82677	21	M24 × 3
53/64"	Fractional inch	0.82812	21.0344	—
21.1 mm	Metric	0.83071	21.1	—
21.2 mm	Metric	0.83465	21.2	—
21.3 mm	Metric	0.83858	21.3	—
21.4 mm	Metric	0.84252	21.4	—
27/32"	Fractional inch	0.84375	21.4312	—
21.5 mm	Metric	0.84646	21.5	—
21.6 mm	Metric	0.85039	21.6	—
21.7 mm	Metric	0.85433	21.7	—
21.8 mm	Metric	0.85827	21.8	—
55/64"	Fractional inch	0.85938	21.8281	—
21.9 mm	Metric	0.8622	21.9	—
22 mm	Metric	0.86614	22	M24 × 2
22.1 mm	Metric	0.87008	22.1	—
22.2 mm	Metric	0.87402	22.2	—
7/8"	Fractional inch	0.875	22.225	—
22.3 mm	Metric	0.87795	22.3	—
22.4 mm	Metric	0.88189	22.4	—
22.5 mm	Metric	0.88583	22.5	—
22.6 mm	Metric	0.88976	22.6	—
57/64"	Fractional inch	0.89062	22.6219	—
22.7 mm	Metric	0.8937	22.7	—
22.8 mm	Metric	0.89764	22.8	—
22.9 mm	Metric	0.90157	22.9	—
23 mm	Metric	0.90551	23	—
29/32"	Fractional inch	0.90625	23.0187	—
23.1 mm	Metric	0.90945	23.1	—
23.2 mm	Metric	0.91339	23.2	—
23.3 mm	Metric	0.91732	23.3	—
23.4 mm	Metric	0.92126	23.4	—
59/64"	Fractional inch	0.92188	23.4156	—
23.5 mm	Metric	0.9252	23.5	—
23.6 mm	Metric	0.92913	23.6	—
23.7 mm	Metric	0.93307	23.7	—
23.8 mm	Metric	0.93701	23.8	—
15/16"	Fractional inch	0.9375	23.8125	—
23.9 mm	Metric	0.94094	23.9	—
24 mm	Metric	0.94488	24	M27 × 3
24.1 mm	Metric	0.94882	24.1	—
24.2 mm	Metric	0.95276	24.2	—
61/64"	Fractional inch	0.95312	24.2094	—
24.3 mm	Metric	0.95669	24.3	—
24.4 mm	Metric	0.96063	24.4	—
24.5 mm	Metric	0.96457	24.5	—
24.6 mm	Metric	0.9685	24.6	—
31/32"	Fractional inch	0.96875	24.6062	—
24.7 mm	Metric	0.97244	24.7	—
24.8 mm	Metric	0.97638	24.8	—
24.9 mm	Metric	0.98031	24.9	—
25 mm	Metric	0.98425	25	—
63/64"	Fractional inch	0.98438	25.0031	—
25.1 mm	Metric	0.98819	25.1	—
25.2 mm	Metric	0.99213	25.2	—
25.3 mm	Metric	0.99606	25.3	—
1"	Fractional inch	1	25.4	—
25.4 mm	Metric	1	25.4	—

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Formula and method

Fractions are converted exactly: inches = numerator ÷ denominator and mm = inches × 25.4 (exact). Number and letter drills use the nominal diameters in the source chart. The nearest drill minimises the absolute difference in mm; tap-drill matches allow ±0.006 mm for rounding.

Worked example

#7 = 0.2010" = 5.105 mm, the tap drill for 1/4-20 UNC; the closest metric drill is 5.1 mm (−0.005 mm) and the closest fractional drill is 13/64" (+0.054 mm).

Assumptions and limits

Number, letter and metric sizes come from the Guhring decimal-equivalents chart (reviewed 2026-10-25); fractional sizes are calculated from exact fractions.
Tap matches come from our tap drill chart (cutting taps, about 75% thread); forming taps need a larger hole.
Drilled holes usually come out slightly oversize; ream when the size is critical.

Frequently asked questions

What size is a #7 drill bit?

0.2010 in = 5.105 mm. It is best known as the tap drill for 1/4-20 UNC.

What size is an F drill?

F = 0.2570 in = 6.528 mm, often used as a close-fit clearance hole for a 1/4 in bolt.

Why do number drills get smaller as the number rises?

Number sizes descend from the Stubs steel wire gauge, where a higher number means thinner wire: #1 is 0.228 in and #80 is 0.0135 in.

What drill do I use for an M6 thread?

M6 × 1 coarse uses a 5.0 mm tap drill; ISO 273 clearance holes are 6.4 / 6.6 / 7.0 mm (fine / medium / coarse).

References

Drill Size Chart practical guide and common questions

What does Drill Size Chart calculate?

Type #7, F, 5/16, 0.201, 6.5 mm, or a thread such as M6 or 1/4-20; results appear as you type. The full chart below can be filtered and downloaded as CSV. Fractions are converted exactly: inches = numerator ÷ denominator and mm = inches × 25.4 (exact). Number and letter drills use the nominal diameters in the source chart. The nearest drill minimises the absolute difference in mm; tap-drill matches allow ±0.006 mm for rounding.

When is this useful?

#7 = 0.2010" = 5.105 mm, the tap drill for 1/4-20 UNC; the closest metric drill is 5.1 mm (−0.005 mm) and the closest fractional drill is 13/64" (+0.054 mm).

How do I enter the inputs?

Enter the inputs for Drill Size Chart: Drill size (#7, F, 5/16, 0.201, 6.5 mm or M6), Treat plain numbers as. Calculate, check the units and assumptions, then copy or download the results.

How should I interpret the results?

Number, letter and metric sizes come from the Guhring decimal-equivalents chart (reviewed 2026-10-25); fractional sizes are calculated from exact fractions. Tap matches come from our tap drill chart (cutting taps, about 75% thread); forming taps need a larger hole. Drilled holes usually come out slightly oversize; ream when the size is critical.

Where are my inputs processed?

Drill Size Chart runs in this browser. Inputs are not uploaded to a calculation server; copying and CSV download require your action. The existing site analytics and advertising still load.