Drill Bit Size Chart

Search and compare fractional, metric, number (#80–#1), and letter (A–Z) drill bit sizes with exact decimal-inch and millimeter equivalents.

Instant Drill Size Lookup Supports # numbers, fractions, letters, decimals, or mm

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Standard Drill Bit Reference Table

Pre-sorted by physical diameter

Size / Designation	Type	Decimal Inches ↑	Millimeters (mm)	Nearest Fractional
#80	number	0.0135 in	0.343 mm	-
#79	number	0.0145 in	0.368 mm	-
1/64"	fractional	0.0156 in	0.397 mm	1/64"
#78	number	0.0160 in	0.406 mm	-
#77	number	0.0180 in	0.457 mm	-
0.50 mm	metric	0.0197 in	0.50 mm	-
#76	number	0.0200 in	0.508 mm	-
#75	number	0.0210 in	0.533 mm	-
#74	number	0.0225 in	0.572 mm	-
0.60 mm	metric	0.0236 in	0.60 mm	-
#73	number	0.0240 in	0.61 mm	-
#72	number	0.0250 in	0.635 mm	-
#71	number	0.0260 in	0.66 mm	-
0.70 mm	metric	0.0276 in	0.70 mm	-
#70	number	0.0280 in	0.711 mm	-
#69	number	0.0292 in	0.742 mm	-
#68	number	0.0310 in	0.787 mm	-
1/32"	fractional	0.0313 in	0.794 mm	1/32"
0.80 mm	metric	0.0315 in	0.80 mm	-
#67	number	0.0320 in	0.813 mm	-
#66	number	0.0330 in	0.838 mm	-
#65	number	0.0350 in	0.889 mm	-
0.90 mm	metric	0.0354 in	0.90 mm	-
#64	number	0.0360 in	0.914 mm	-
#63	number	0.0370 in	0.94 mm	-
#62	number	0.0380 in	0.965 mm	-
#61	number	0.0390 in	0.991 mm	-
1.00 mm	metric	0.0394 in	1.00 mm	-
#60	number	0.0400 in	1.016 mm	-
#59	number	0.0410 in	1.041 mm	-
#58	number	0.0420 in	1.067 mm	-
#57	number	0.0430 in	1.092 mm	-
1.10 mm	metric	0.0433 in	1.10 mm	-
#56	number	0.0465 in	1.181 mm	-
3/64"	fractional	0.0469 in	1.191 mm	3/64"
1.20 mm	metric	0.0472 in	1.20 mm	-
1.25 mm	metric	0.0492 in	1.25 mm	-
1.30 mm	metric	0.0512 in	1.30 mm	-
#55	number	0.0520 in	1.321 mm	-
#54	number	0.0550 in	1.397 mm	-
1.40 mm	metric	0.0551 in	1.40 mm	-
1.50 mm	metric	0.0591 in	1.50 mm	-
#53	number	0.0595 in	1.511 mm	-
1/16"	fractional	0.0625 in	1.587 mm	1/16"
1.60 mm	metric	0.0630 in	1.60 mm	-
#52	number	0.0635 in	1.613 mm	-
1.70 mm	metric	0.0669 in	1.70 mm	-
#51	number	0.0670 in	1.702 mm	-
1.75 mm	metric	0.0689 in	1.75 mm	-
#50	number	0.0700 in	1.778 mm	-
1.80 mm	metric	0.0709 in	1.80 mm	-
#49	number	0.0730 in	1.854 mm	-
1.90 mm	metric	0.0748 in	1.90 mm	-
#48	number	0.0760 in	1.93 mm	-
5/64"	fractional	0.0781 in	1.984 mm	5/64"
#47	number	0.0785 in	1.994 mm	-
2.00 mm	metric	0.0787 in	2.00 mm	-
2.05 mm	metric	0.0807 in	2.05 mm	-
#46	number	0.0810 in	2.057 mm	-
#45	number	0.0820 in	2.083 mm	-
2.10 mm	metric	0.0827 in	2.10 mm	-
#44	number	0.0860 in	2.184 mm	-
2.20 mm	metric	0.0866 in	2.20 mm	-
2.25 mm	metric	0.0886 in	2.25 mm	-
#43	number	0.0890 in	2.261 mm	-
2.30 mm	metric	0.0906 in	2.30 mm	-
#42	number	0.0935 in	2.375 mm	-
3/32"	fractional	0.0938 in	2.381 mm	3/32"
2.40 mm	metric	0.0945 in	2.40 mm	-
#41	number	0.0960 in	2.438 mm	-
#40	number	0.0980 in	2.489 mm	-
2.50 mm	metric	0.0984 in	2.50 mm	-
#39	number	0.0995 in	2.527 mm	-
#38	number	0.1015 in	2.578 mm	-
2.60 mm	metric	0.1024 in	2.60 mm	-
#37	number	0.1040 in	2.642 mm	-
2.70 mm	metric	0.1063 in	2.70 mm	-
#36	number	0.1065 in	2.705 mm	-
2.75 mm	metric	0.1083 in	2.75 mm	-
7/64"	fractional	0.1094 in	2.778 mm	7/64"
#35	number	0.1100 in	2.794 mm	-
2.80 mm	metric	0.1102 in	2.80 mm	-
#34	number	0.1110 in	2.819 mm	-
#33	number	0.1130 in	2.87 mm	-
2.90 mm	metric	0.1142 in	2.90 mm	-
#32	number	0.1160 in	2.946 mm	-
3.00 mm	metric	0.1181 in	3.00 mm	-
#31	number	0.1200 in	3.048 mm	-
3.10 mm	metric	0.1220 in	3.10 mm	-
1/8"	fractional	0.1250 in	3.175 mm	1/8"
3.20 mm	metric	0.1260 in	3.20 mm	-
3.25 mm	metric	0.1280 in	3.25 mm	-
#30	number	0.1285 in	3.264 mm	-
3.30 mm	metric	0.1299 in	3.30 mm	-
3.40 mm	metric	0.1339 in	3.40 mm	-
#29	number	0.1360 in	3.454 mm	-
3.50 mm	metric	0.1378 in	3.50 mm	-
#28	number	0.1405 in	3.569 mm	-
9/64"	fractional	0.1406 in	3.572 mm	9/64"
3.60 mm	metric	0.1417 in	3.60 mm	-
#27	number	0.1440 in	3.658 mm	-
3.70 mm	metric	0.1457 in	3.70 mm	-
#26	number	0.1470 in	3.734 mm	-
3.75 mm	metric	0.1476 in	3.75 mm	-
#25	number	0.1495 in	3.797 mm	-
3.80 mm	metric	0.1496 in	3.80 mm	-
#24	number	0.1520 in	3.861 mm	-
3.90 mm	metric	0.1535 in	3.90 mm	-
#23	number	0.1540 in	3.912 mm	-
5/32"	fractional	0.1563 in	3.969 mm	5/32"
#22	number	0.1570 in	3.988 mm	-
4.00 mm	metric	0.1575 in	4.00 mm	-
#21	number	0.1590 in	4.039 mm	-
#20	number	0.1610 in	4.089 mm	-
4.10 mm	metric	0.1614 in	4.10 mm	-
4.20 mm	metric	0.1654 in	4.20 mm	-
#19	number	0.1660 in	4.216 mm	-
4.25 mm	metric	0.1673 in	4.25 mm	-
4.30 mm	metric	0.1693 in	4.30 mm	-
#18	number	0.1695 in	4.305 mm	-
11/64"	fractional	0.1719 in	4.366 mm	11/64"
#17	number	0.1730 in	4.394 mm	-
4.40 mm	metric	0.1732 in	4.40 mm	-
#16	number	0.1770 in	4.496 mm	-
4.50 mm	metric	0.1772 in	4.50 mm	-
#15	number	0.1800 in	4.572 mm	-
4.60 mm	metric	0.1811 in	4.60 mm	-
#14	number	0.1820 in	4.623 mm	-
#13	number	0.1850 in	4.699 mm	-
4.70 mm	metric	0.1850 in	4.70 mm	-
4.75 mm	metric	0.1870 in	4.75 mm	-
3/16"	fractional	0.1875 in	4.763 mm	3/16"
#12	number	0.1890 in	4.801 mm	-
4.80 mm	metric	0.1890 in	4.80 mm	-
#11	number	0.1910 in	4.851 mm	-
4.90 mm	metric	0.1929 in	4.90 mm	-
#10	number	0.1935 in	4.915 mm	-
#9	number	0.1960 in	4.978 mm	-
5.00 mm	metric	0.1969 in	5.00 mm	-
#8	number	0.1990 in	5.055 mm	-
5.10 mm	metric	0.2008 in	5.10 mm	-
#7	number	0.2010 in	5.105 mm	13/64"
13/64"	fractional	0.2031 in	5.159 mm	13/64"
#6	number	0.2040 in	5.182 mm	-
5.20 mm	metric	0.2047 in	5.20 mm	-
#5	number	0.2055 in	5.22 mm	-
5.25 mm	metric	0.2067 in	5.25 mm	-
5.30 mm	metric	0.2087 in	5.30 mm	-
#4	number	0.2090 in	5.309 mm	-
5.40 mm	metric	0.2126 in	5.40 mm	-
#3	number	0.2130 in	5.41 mm	-
5.50 mm	metric	0.2165 in	5.50 mm	-
7/32"	fractional	0.2188 in	5.556 mm	7/32"
5.60 mm	metric	0.2205 in	5.60 mm	-
#2	number	0.2210 in	5.613 mm	-
5.70 mm	metric	0.2244 in	5.70 mm	-
5.75 mm	metric	0.2264 in	5.75 mm	-
#1	number	0.2280 in	5.791 mm	-
5.80 mm	metric	0.2283 in	5.80 mm	-
5.90 mm	metric	0.2323 in	5.90 mm	-
A	letter	0.2340 in	5.944 mm	-
15/64"	fractional	0.2344 in	5.953 mm	15/64"
6.00 mm	metric	0.2362 in	6.00 mm	-
B	letter	0.2380 in	6.045 mm	-
6.10 mm	metric	0.2402 in	6.10 mm	-
C	letter	0.2420 in	6.147 mm	-
6.20 mm	metric	0.2441 in	6.20 mm	-
D	letter	0.2460 in	6.248 mm	-
6.25 mm	metric	0.2461 in	6.25 mm	-
6.30 mm	metric	0.2480 in	6.30 mm	-
E	letter	0.2500 in	6.35 mm	1/4"
1/4"	fractional	0.2500 in	6.35 mm	1/4"
6.40 mm	metric	0.2520 in	6.40 mm	-
6.50 mm	metric	0.2559 in	6.50 mm	-
F	letter	0.2570 in	6.528 mm	-
6.60 mm	metric	0.2598 in	6.60 mm	-
G	letter	0.2610 in	6.629 mm	-
6.70 mm	metric	0.2638 in	6.70 mm	-
17/64"	fractional	0.2656 in	6.747 mm	17/64"
6.75 mm	metric	0.2657 in	6.75 mm	-
H	letter	0.2660 in	6.756 mm	-
6.80 mm	metric	0.2677 in	6.80 mm	-
6.90 mm	metric	0.2717 in	6.90 mm	-
I	letter	0.2720 in	6.909 mm	-
7.00 mm	metric	0.2756 in	7.00 mm	-
J	letter	0.2770 in	7.036 mm	-
7.10 mm	metric	0.2795 in	7.10 mm	-
K	letter	0.2810 in	7.137 mm	-
9/32"	fractional	0.2813 in	7.144 mm	9/32"
7.20 mm	metric	0.2835 in	7.20 mm	-
7.25 mm	metric	0.2854 in	7.25 mm	-
7.30 mm	metric	0.2874 in	7.30 mm	-
L	letter	0.2900 in	7.366 mm	-
7.40 mm	metric	0.2913 in	7.40 mm	-
M	letter	0.2950 in	7.493 mm	-
7.50 mm	metric	0.2953 in	7.50 mm	-
19/64"	fractional	0.2969 in	7.541 mm	19/64"
7.60 mm	metric	0.2992 in	7.60 mm	-
N	letter	0.3020 in	7.671 mm	-
7.70 mm	metric	0.3031 in	7.70 mm	-
7.75 mm	metric	0.3051 in	7.75 mm	-
7.80 mm	metric	0.3071 in	7.80 mm	-
7.90 mm	metric	0.3110 in	7.90 mm	-
5/16"	fractional	0.3125 in	7.938 mm	5/16"
8.00 mm	metric	0.3150 in	8.00 mm	-
O	letter	0.3160 in	8.026 mm	-
8.10 mm	metric	0.3189 in	8.10 mm	-
8.20 mm	metric	0.3228 in	8.20 mm	-
P	letter	0.3230 in	8.204 mm	-
8.25 mm	metric	0.3248 in	8.25 mm	-
8.30 mm	metric	0.3268 in	8.30 mm	-
21/64"	fractional	0.3281 in	8.334 mm	21/64"
8.40 mm	metric	0.3307 in	8.40 mm	-
Q	letter	0.3320 in	8.433 mm	-
8.50 mm	metric	0.3346 in	8.50 mm	-
8.60 mm	metric	0.3386 in	8.60 mm	-
R	letter	0.3390 in	8.611 mm	-
8.70 mm	metric	0.3425 in	8.70 mm	-
11/32"	fractional	0.3438 in	8.731 mm	11/32"
8.75 mm	metric	0.3445 in	8.75 mm	-
8.80 mm	metric	0.3465 in	8.80 mm	-
S	letter	0.3480 in	8.839 mm	-
8.90 mm	metric	0.3504 in	8.90 mm	-
9.00 mm	metric	0.3543 in	9.00 mm	-
T	letter	0.3580 in	9.093 mm	-
9.10 mm	metric	0.3583 in	9.10 mm	-
23/64"	fractional	0.3594 in	9.128 mm	23/64"
9.20 mm	metric	0.3622 in	9.20 mm	-
9.25 mm	metric	0.3642 in	9.25 mm	-
9.30 mm	metric	0.3661 in	9.30 mm	-
U	letter	0.3680 in	9.347 mm	-
9.40 mm	metric	0.3701 in	9.40 mm	-
9.50 mm	metric	0.3740 in	9.50 mm	-
3/8"	fractional	0.3750 in	9.525 mm	3/8"
V	letter	0.3770 in	9.576 mm	-
9.60 mm	metric	0.3780 in	9.60 mm	-
9.70 mm	metric	0.3819 in	9.70 mm	-
9.75 mm	metric	0.3839 in	9.75 mm	-
9.80 mm	metric	0.3858 in	9.80 mm	-
W	letter	0.3860 in	9.804 mm	-
9.90 mm	metric	0.3898 in	9.90 mm	-
25/64"	fractional	0.3906 in	9.922 mm	25/64"
10.00 mm	metric	0.3937 in	10.00 mm	-
X	letter	0.3970 in	10.084 mm	-
10.20 mm	metric	0.4016 in	10.20 mm	-
Y	letter	0.4040 in	10.262 mm	-
13/32"	fractional	0.4063 in	10.319 mm	13/32"
Z	letter	0.4130 in	10.49 mm	-
10.50 mm	metric	0.4134 in	10.50 mm	-
27/64"	fractional	0.4219 in	10.716 mm	27/64"
10.80 mm	metric	0.4252 in	10.80 mm	-
11.00 mm	metric	0.4331 in	11.00 mm	-
7/16"	fractional	0.4375 in	11.113 mm	7/16"
11.20 mm	metric	0.4409 in	11.20 mm	-
11.50 mm	metric	0.4528 in	11.50 mm	-
29/64"	fractional	0.4531 in	11.509 mm	29/64"
11.80 mm	metric	0.4646 in	11.80 mm	-
15/32"	fractional	0.4688 in	11.906 mm	15/32"
12.00 mm	metric	0.4724 in	12.00 mm	-
12.20 mm	metric	0.4803 in	12.20 mm	-
31/64"	fractional	0.4844 in	12.303 mm	31/64"
12.50 mm	metric	0.4921 in	12.50 mm	-
1/2"	fractional	0.5000 in	12.70 mm	1/2"
12.80 mm	metric	0.5039 in	12.80 mm	-
13.00 mm	metric	0.5118 in	13.00 mm	-
33/64"	fractional	0.5156 in	13.097 mm	33/64"
17/32"	fractional	0.5313 in	13.494 mm	17/32"
13.50 mm	metric	0.5315 in	13.50 mm	-
35/64"	fractional	0.5469 in	13.891 mm	35/64"
14.00 mm	metric	0.5512 in	14.00 mm	-
9/16"	fractional	0.5625 in	14.287 mm	9/16"
14.50 mm	metric	0.5709 in	14.50 mm	-
37/64"	fractional	0.5781 in	14.684 mm	37/64"
15.00 mm	metric	0.5906 in	15.00 mm	-
19/32"	fractional	0.5938 in	15.081 mm	19/32"
39/64"	fractional	0.6094 in	15.478 mm	39/64"
15.50 mm	metric	0.6102 in	15.50 mm	-
5/8"	fractional	0.6250 in	15.875 mm	5/8"
16.00 mm	metric	0.6299 in	16.00 mm	-
41/64"	fractional	0.6406 in	16.272 mm	41/64"
16.50 mm	metric	0.6496 in	16.50 mm	-
21/32"	fractional	0.6563 in	16.669 mm	21/32"
17.00 mm	metric	0.6693 in	17.00 mm	-
43/64"	fractional	0.6719 in	17.066 mm	43/64"
11/16"	fractional	0.6875 in	17.462 mm	11/16"
17.50 mm	metric	0.6890 in	17.50 mm	-
45/64"	fractional	0.7031 in	17.859 mm	45/64"
18.00 mm	metric	0.7087 in	18.00 mm	-
23/32"	fractional	0.7188 in	18.256 mm	23/32"
18.50 mm	metric	0.7283 in	18.50 mm	-
47/64"	fractional	0.7344 in	18.653 mm	47/64"
19.00 mm	metric	0.7480 in	19.00 mm	-
3/4"	fractional	0.7500 in	19.05 mm	3/4"
49/64"	fractional	0.7656 in	19.447 mm	49/64"
19.50 mm	metric	0.7677 in	19.50 mm	-
25/32"	fractional	0.7813 in	19.844 mm	25/32"
20.00 mm	metric	0.7874 in	20.00 mm	-
51/64"	fractional	0.7969 in	20.241 mm	51/64"
20.50 mm	metric	0.8071 in	20.50 mm	-
13/16"	fractional	0.8125 in	20.637 mm	13/16"
21.00 mm	metric	0.8268 in	21.00 mm	-
53/64"	fractional	0.8281 in	21.034 mm	53/64"
27/32"	fractional	0.8438 in	21.431 mm	27/32"
21.50 mm	metric	0.8465 in	21.50 mm	-
55/64"	fractional	0.8594 in	21.828 mm	55/64"
22.00 mm	metric	0.8661 in	22.00 mm	-
7/8"	fractional	0.8750 in	22.225 mm	7/8"
22.50 mm	metric	0.8858 in	22.50 mm	-
57/64"	fractional	0.8906 in	22.622 mm	57/64"
23.00 mm	metric	0.9055 in	23.00 mm	-
29/32"	fractional	0.9063 in	23.019 mm	29/32"
59/64"	fractional	0.9219 in	23.416 mm	59/64"
23.50 mm	metric	0.9252 in	23.50 mm	-
15/16"	fractional	0.9375 in	23.813 mm	15/16"
24.00 mm	metric	0.9449 in	24.00 mm	-
61/64"	fractional	0.9531 in	24.209 mm	61/64"
24.50 mm	metric	0.9646 in	24.50 mm	-
31/32"	fractional	0.9688 in	24.606 mm	31/32"
25.00 mm	metric	0.9843 in	25.00 mm	-
63/64"	fractional	0.9844 in	25.003 mm	63/64"
1"	fractional	1.0000 in	25.40 mm	1"
1-1/16"	fractional	1.0625 in	26.988 mm	1-1/16"
1-1/8"	fractional	1.1250 in	28.575 mm	1-1/8"
1-3/16"	fractional	1.1875 in	30.163 mm	1-3/16"
1-1/4"	fractional	1.2500 in	31.75 mm	1-1/4"
1-5/16"	fractional	1.3125 in	33.337 mm	1-5/16"
1-3/8"	fractional	1.3750 in	34.925 mm	1-3/8"
1-7/16"	fractional	1.4375 in	36.513 mm	1-7/16"
1-1/2"	fractional	1.5000 in	38.10 mm	1-1/2"

Understanding Drill Sizing Systems

Fractional Inch Drills: Sized in standard binary inch fractions from 1/64" up to 1-1/2" and larger. Common increments are 1/64" (0.0156") and 1/32" (0.03125").
Number Drills (#80 to #1): Derived from the historic Stubs steel wire gage, standardized in ASME B94.11M. Sizing runs in reverse: #80 is the smallest (0.0135") and #1 is the largest (0.2280").
Letter Drills (A to Z): Bridge the gap between wire gage sizes and fractional inches, spanning from Letter A (0.2340") to Letter Z (0.4130"). Note that Letter E (0.2500") is exact to 1/4".
Metric Drills (mm): Defined directly in millimeters. Standard jobber drill sets typically step by 0.1 mm increments from 1.0 mm to 10.0 mm, and 0.5 mm steps for larger diameters.

Decimal & Metric Conversions

All inch-to-millimeter conversions across this reference use the exact international standard defined as 1 inch = 25.4 millimeters.

Millimeters = Decimal Inches × 25.4

Decimal Inches = Millimeters ÷ 25.4

Machinist convention typically records decimal inches to 4 decimal places (0.0001" or tenths of a thousandth) and millimeters to 2 or 3 decimal places depending on tool grinding tolerances.

How to Use This Chart in the Workshop

Quick Diameter Lookup: Enter any drill number (e.g. #7), fraction (13/64), letter (F), or metric dimension into the search box above for instant decimal and metric values.
Nearest Size Comparison: If you measure a hole or dowel pin with calipers (e.g., 5.15 mm or 0.205"), enter the raw dimension to see the closest smaller and larger standard tooling sizes with exact offset differences.
Print Reference: Click the Print Table button to generate a clean, distraction-free shop reference card formatted for 8.5×11" paper.

Standards & Technical References

View Full Methodology →

ASME B94.11M – Twist Drills: Standard specification for straight and taper shank twist drills, defining wire gage numbers (#80 to #1), letter sizes (A to Z), and fractional inch increments.
Machinery's Handbook (31st Edition): Standard reference work for mechanical engineers, designers, manufacturing engineers, and machinists.