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Drill Bit Size Chart

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Convert fractional, letter, number, and decimal drill bit sizes with one reference chart.

Decimal Inches	Fractional Size	Number Size	Letter Size	Metric Size (mm)
0.0135		80
0.0145		79
0.0156	1/64
0.0160		78
0.0180		77
0.0197				0.5
0.0200		76
0.0210		75
0.0225		74
0.0240		73
0.0250		72
0.0260		71
0.0280		70
0.0292		69
0.0295				0.75
0.0310		68
0.0312	1/32
0.0320		67
0.0330		66
0.0350		65
0.0360		64
0.0370		63
0.0380		62
0.0390		61
0.0394				1
0.0400		60
0.0410		59
0.0420		58
0.0430		57
0.0465		56
0.0469	3/64
0.0492				1.25
0.0520		55
0.0550		54
0.0591				1.5
0.0595		53
0.0625	1/16
0.0635		52
0.0670		51
0.0689				1.75
0.0700		50
0.0730		49
0.0760		48
0.0781	5/64
0.0785		47
0.0787				2
0.0810		46
0.0820		45
0.0860		44
0.0886				2.25
0.0890		43
0.0935		42
0.0938	3/32
0.0960		41
0.0980		40
0.0984				2.5
0.0995		39
0.1015		38
0.1040		37
0.1065		36
0.1083				2.75
0.1094	7/64
0.1100		35
0.1110		34
0.1130		33
0.1160		32
0.1181				3
0.1200		31
0.1250	1/8
0.1280				3.25
0.1285		30
0.1360		29
0.1378				3.5
0.1405		28
0.1406	9/64
0.1440		27
0.1470		26
0.1476				3.75
0.1495		25
0.1520		24
0.1540		23
0.1562	5/32
0.1570		22
0.1575				4
0.1590		21
0.1610		20
0.1660		19
0.1673				4.25
0.1695		18
0.1719	11/64
0.1730		17
0.1770		16
0.1772				4.5
0.1800		15
0.1820		14
0.1850		13
0.1870				4.75
0.1875	3/16
0.1890		12
0.1910		11
0.1935		10
0.1960		9
0.1969				5
0.1990		8
0.2010		7
0.2031	13/64
0.2040		6
0.2055		5
0.2067				5.25
0.2090		4
0.2130		3
0.2165				5.5
0.2188	7/32
0.2210		2
0.2264				5.75
0.2280		1
0.2340			A
0.2344	15/64
0.2362				6
0.2380			B
0.2420			C
0.2460			D
0.2461				6.25
0.2500	1/4		E
0.2559				6.5
0.2570			F
0.2610			G
0.2656	17/64
0.2657				6.75
0.2660			H
0.2720			I
0.2756				7
0.2770			J
0.2810			K
0.2812	9/32
0.2854				7.25
0.2900			L
0.2950			M
0.2953				7.5
0.2969	19/64
0.3020			N
0.3051				7.75
0.3125	5/16
0.3150				8
0.3160			O
0.3230			P
0.3248				8.25
0.3281	21/64
0.3320			Q
0.3346				8.5
0.3390			R
0.3438	11/32
0.3445				8.75
0.3480			S
0.3543				9
0.3580			T
0.3594	23/64
0.3642				9.25
0.3680			U
0.3740				9.5
0.3750	3/8
0.3770			V
0.3839				9.75
0.3860			W
0.3906	25/64
0.3937				10
0.3970			X
0.4040			Y
0.4063	13/32
0.4130			Z
0.4134				10.5
0.4219	27/64
0.4331				11
0.4375	7/16
0.4528				11.5
0.4531	29/64
0.4688	15/32
0.4724				12
0.4844	31/64
0.4921				12.5
0.5000	1/2
0.5118				13
0.5156	33/64
0.5312	17/32
0.5315				13.5
0.5469	35/64
0.5512				14
0.5625	9/16
0.5709				14.5
0.5781	37/64
0.5906				15
0.5938	19/32
0.6094	39/64
0.6102				15.5
0.6250	5/8
0.6299				16
0.6406	41/64
0.6496				16.5
0.6562	21/32
0.6693				17
0.6719	43/64
0.6875	11/16
0.6890				17.5
0.7031	45/64
0.7087				18
0.7188	23/32
0.7283				18.5
0.7344	47/64
0.7480				19
0.7500	3/4
0.7656	49/64
0.7677				19.5
0.7813	25/32
0.7874				20
0.7969	51/64
0.8071				20.5
0.8125	13/16
0.8268				21
0.8281	53/64
0.8438	27/32
0.8465				21.5
0.8594	55/64
0.8661				22
0.8750	7/8
0.8858				22.5
0.8906	57/64
0.9055				23
0.9062	29/32
0.9219	59/64
0.9252				23.5
0.9375	15/16
0.9449				24
0.9531	61/64
0.9646				24.5
0.9688	31/32
0.9843				25
0.9844	63/64
1.0000	1

How to Use This Drill Bit Size Chart

Use this chart to compare fractional, letter, number, and decimal drill bit sizes by diameter. It is most useful when a drawing, fastener spec, or tap chart calls out one drill system and the drill set on hand uses another.

Convert to Decimal Inches

Decimal equivalents make it easier to compare close drill sizes, check fit tolerances, and choose the nearest available bit.

Match Number and Letter Drills

Numbered wire gauge drills and letter drills fill the gaps between common fractional sizes, which matters for tapped holes and precise clearance holes.

Pick the Nearest Practical Size

When the exact drill size is unavailable, compare nearby decimal diameters before deciding whether to go slightly larger or smaller for the operation.

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