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By far the best drill chart I’ve ever found can be found at Robert May’s Astronomy page:

http://bobmay.astronomy.net/misc/drillchart.htm

Hat’s off to Rob for such a great resource.

Here is a quick copy for your reference.

Drill Bit Size Chart to 1 inch Diameter

Legend Fractional Inch Letter Drill Millimeters Number Drill
Millimeters	Inches	Designation	Tap Drill/Pilot Drill Uses
.3429mm	.0135″	#80
.3683mm	.0145″	#79
.3969mm	.015625″	1/64″	#0 Pilot, Soft-Wood
.4064mm	.016″	#78
.4572mm	.018″	#77
.5mm	.0197″
.508mm	.02″	#76
.5334mm	.021″	#75
.5715mm	.0225″	#74
.6096mm	.024″	#73
.635mm	.025″	#72
.6604mm	.026″	#71
.7112mm	.028″	#70
.74168mm	.0292″	#69
.75mm	.0295″		M1x.25 coarse
.7874mm	.031″	#68
.7938mm	.03125″	1/32″	#0 Pilot, Hard-Wood #1 Pilot, Hard & Soft-Wood #2 Pilot, Soft-Wood
.8128mm	.032″	#67
.8382mm	.033″	#66
.85mm	.0335″		M1.1x.25 coarse
.889mm	.035″	#65
.9144mm	.036″	#64
.9398mm	.037″	#63
.95mm	.0374″		M1.2x.25 coarse
.9652mm	.038″	#62
.9906mm	.039″	#61
1mm	.0394″
1.016mm	.04″	#60
1.0414mm	.041″	#59
1.0668mm	.042″	#58
1.0922mm	.043″	#57
1.1mm	.0433″		M1.4x.3 coarse
1.1811mm	.0465″	#56
1.1906mm	.046875″	3/64″	#0-80 UNF#2 Pilot, Hard-wood, #3 Pilot, Soft-Wood #4 Pilot, Soft-Wood
1.25mm	.0492″		M1.6x.35 coarse
1.3mm	.0512″		M1.7x.35 coarse
1.3208mm	.052″	#55
1.397mm	.055″	#54
1.45mm	.0571″		M1.8x.35 coarse
1.5mm	.0591″
1.5113mm	.0595″	#53	#1-64 UNC, #1-72 UNF
1.5875mm	.0625″	1/16″	#0 Wood Shank Hole, #3 Pilot, Hard-Wood, #4 Pilot, Hard-wood #5 Pilot, Soft-wood, #6 Pilot, Soft-wood, #7 Pilot, Soft-wood
1.6mm	.063″		M2x.4 coarse
1.6129mm	.0635″	#52
1.7018mm	.067″	#51
1.75mm	.0689″		M2.2x.45 coarse
1.778mm	.07″	#50	#2-64 UNF, #2-56 UNC
1.8542mm	.073″	#49
1.9304mm	.076″	#48
1.9844mm	.078125″	5/64″	#1 Wood Shank Hole#5 Pilot, Hard-wood, #6 Pilot, Hard-wood #8 Pilot, Soft-wood, #9 Pilot, Soft-wood
1.9939mm	.0785″	#47	#3-48 UNC
2mm	.0787″
2.05mm	.0807″		M2.5x.45 coarse
2.0574mm	.081″	#46
2.0828mm	.082″	#45	#3-56 UNF
2.1844mm	.086″	#44
2.2606mm	.089″	#43	#4-40 UNC
2.3749mm	.0935″	#42	#4-48 UNF
2.3813mm	.09375″	3/32″	#2 Wood Shank Hole, #7 Pilot, Hard-wood, #8 Pilot, Hard-wood, #10 Pilot, Soft-wood, #11 Pilot, Soft-wood
2.4384mm	.096″	#41
2.4892mm	.098″	#40
2.5mm	.0984″		M3x.5 coarse
2.5273mm	.0995″	#39
2.5781mm	.1015″	#38	#5-40 UNC
2.6416mm	.104″	#37	#5-44 UNF
2.7051mm	.1065″	#36	#6-32 UNC
2.7781mm	.109375″	7/64″	#3 Wood Shank Hole, #4 Wood Shank Hole, #9 Pilot, Hard-wood #10 Pilot, Hard-wood, #12 Pilot, Soft-wood, #14 Pilot, Soft-wood
2.794mm	.11″	#35
2.8194mm	.111″	#34
2.8702mm	.113″	#33	#6-40 UNF
2.9mm	.1142″		M3.5x.6 coarse
2.9464mm	.116″	#32
3mm	.1181″
3.048mm	.12″	#31
3.175mm	.125″	1/8″	#5 Wood Shank Hole, #11 Pilot, Hard-wood, #12 Pilot, Hard-wood
3.2639mm	.1285″	#30
3.3mm	.1299″		M4x.7 coarse
3.4544mm	.136″	#29	#8-32 UNC, #8-36 UNF
3.5mm	.1378″		M4x.5 Fine
3.5687mm	.1405″	#28
3.5719mm	.140625″	9/64″	#6 Wood Shank Hole, #14 Pilot, Hard-wood, #16 Pilot, Soft-wood #18 Pilot, Soft-wood
3.6mm	.1417″		M4x.35 Fine
3.6576mm	.144″	#27
3.7mm	.1457″		M4.5x.75 coarse
3.7338mm	.147″	#26
3.7973mm	.1495″	#25	#10-24 UNC
3.8608mm	.152″	#24
3.9116mm	.154″	#23
3.9688mm	.15625″	5/32″	#7 Wood Shank Hole, #16 Pilot, Hard-wood
3.9878mm	.157″	#22
4mm	.1575″
4.0386mm	.159″	#21	#10-32 UNF
4.0894mm	.161″	#20
4.2mm	.1654″		M5x.8 coarse
4.2164mm	.166″	#19
4.3053mm	.1695″	#18
4.3656mm	.171875″	11/64″	#8 Wood Shank Hole, #20 Pilot, Soft-wood
4.3942mm	.173″	#17	#12-24 UNC
4.4958mm	.177″	#16
4.5mm	.1772″		M5x.5 Fine
4.572mm	.18″	#15	#12-28 UNF
4.6228mm	.182″	#14
4.699mm	.185″	#13
4.7625mm	.1875″	3/16″	#9 Wood Shank Hole, #10 Wood Shank Hole, #18 Pilot, Hardwood
4.8006mm	.189″	#12
4.8514mm	.191″	#11
4.9149mm	.1935″	#10
4.9784mm	.196″	# 9
5mm	.1969″		M6x1 coarse
5.0546mm	.199″	# 8
5.1054mm	.201″	# 7	1/4″-20 UNC
5.1594mm	.203125″	13/64″	#11 Wood Shank Hole, #20 Pilot, Hard-wood
5.1816mm	.204″	# 6
5.2197mm	.2055″	# 5
5.25mm	.2067″		M6x.75 Fine
5.3086mm	.209″	# 4
5.4102mm	.213″	# 3	1/4″-28 UNF
5.5mm	.2165″		M6x.5 Fine
5.5563mm	.21875″	7/32″	#12 Wood Shank Hole
5.6134mm	.221″	# 2
5.7912mm	.228″	# 1
5.9436mm	.234″	A
5.9531mm	.234375″	15/64″
6mm	.2362″		M7x1 coarse
6.0452mm	.238″	B
6.1468mm	.242″	C
6.2484mm	.246″	D	1/16″-27 NPT
6.25mm	.2461″		M7x.75 Fine
6.35mm	.25″	1/4″	#14 Wood Shank Hole
6.35mm	.25″	E
6.5mm	.2559″
6.5278mm	.257″	F	5/16″-18 UNC
6.6294mm	.261″	G
6.7469mm	.265625″	17/64″	#16 Wood Shank Hole
6.7564mm	.266″	H
6.8mm	.2677″		M8x1.25 coarse
6.9088mm	.272″	I	5/16″-24 UNF
7mm	.2756″		M8x.5 Fine
7.0358mm	.277″	J
7.1374mm	.281″	K
7.1438mm	.28125″	9/32″
7.25mm	.2854″		M8x.75 Fine
7.366mm	.29″	L
7.493mm	.295″	M
7.5mm	.2953″		M8x1 Fine
7.5406mm	.296875″	19/64″	#18 Wood Shank Hole
7.6708mm	.302″	N
7.8mm	.3071″		M9x1.25 coarse
7.9375mm	.3125″	5/16″	3/8″-16 UNC
8mm	.315″		M9x1 Fine
8.0264mm	.316″	O
8.2042mm	.323″	P
8.3344mm	.328125″	21/64″	#20 Wood Shank Hole
8.4328mm	.332″	Q	3/8″-24 UNF
8.5mm	.3346″		M10x1.5 coarse
8.6106mm	.339″	R	1/8″-27 NPT
8.7313mm	.34375″	11/32″
8.8mm	.3465″		M10x1.25 Fine
8.8392mm	.348″	S
9mm	.3543″		M10x1 Fine
9.0932mm	.358″	T	7/16″-14 UNC
9.1281mm	.359375″	23/64″
9.25mm	.3642″		M10x.75 Fine
9.3472mm	.368″	U
9.5mm	.374″		M11x1.5 coarse
9.525mm	.375″	3/8″
9.5758mm	.377″	V
9.8044mm	.386″	W
9.9219mm	.390625″	25/64″	7/16″-20 UNF
10mm	.3937″		M11x1 Fine
10.0838mm	.397″	X
10.2mm	.4016″		M12x1.75 coarse
10.2616mm	.404″	Y
10.3188mm	.40625″	13/32″
10.4902mm	.413″	Z
10.5mm	.4134″		M12x1.5 Fine
10.7156mm	.421875″	27/64″	1/2″-13 UNC
11mm	.4331″		M12x1 Fine
11.1125mm	.4375″	7/16″	1/4″-18 NPT
11.25mm	.4429″		M12x.75 Fine
11.5mm	.4528″
11.5094mm	.453125″	29/64″	1/2″-20 UNF
11.9063mm	.46875″	15/32″
12mm	.4724″		M14x2 coarse
12.3031mm	.484375″	31/64″	9/16″-12 UNC
12.5mm	.4921″		M14x1.5 Fine
12.7mm	.5″	1/2″
12.8mm	.5039″		M14x1.25 Fine
13mm	.5118″		M14x1 Fine
13.0969mm	.515625″	33/64″	9/16″-18 UNF
13.4938mm	.53125″	17/32″	5/8″-11 UNC
13.5mm	.5315″
13.8906mm	.546875″	35/64″
14mm	.5512″		M16x2 coarse
14.2875mm	.5625″	9/16″	5/8″-18 UNF
14.5mm	.5709″		M16x1.5 Fine
14.6844mm	.578125″	37/64″	3/8″-18 NPT
15mm	.5906″		M16x1 Fine
15.0813mm	.59375″	19/32″
15.4781mm	.609375″	39/64″
15.5mm	.6102″		M18x2.5 coarse
15.875mm	.625″	5/8″
16mm	.6299″		M18x2 Fine
16.2719mm	.640625″	41/64″	3/4″-10 UNC
16.5mm	.6496″
16.6688mm	.65625″	21/32″
17mm	.6693″		M18x1 Fine
17.0656mm	.671875″	43/64″
17.4625mm	.6875″	11/16″	3/4″-16 UNF
17.5mm	.689″		M20x2.5 coarse
17.8594mm	.703125″	45/64″	1/2″-14 NPT
18mm	.7087″		M20x2 Fine
18.2563mm	.71875″	23/32″
18.5mm	.7283″		M20x1.5 Fine
18.6531mm	.734375″	47/64″
19mm	.748″		M20x1 Fine
19.05mm	.75″	3/4″
19.4469mm	.765625″	49/64″	7/8″-9 UNC
19.5mm	.7677″		M22x2.5 coarse
19.8438mm	.78125″	25/32″
20mm	.7874″		M22x2 Fine
20.2406mm	.796875″	51/64″
20.5mm	.8071″		M22x1.5 Fine
20.6375mm	.8125″	13/16″	7/8″-14 UNF
21mm	.8268″		M24x3 coarseM22x1 Fine
21.0344mm	.828125″	53/64″
21.4313mm	.84375″	27/32″
21.5mm	.8465″
21.8281mm	.859375″	55/64″
22mm	.8661″		M24x2 Fine
22.225mm	.875″	7/8″	1″-8 UNC
22.5mm	.8858″		M24x1.5 Fine
22.6219mm	.890625″	57/64″
23mm	.9055″
23.0188mm	.90625″	29/32″	1″-12 UNF
23.4156mm	.921875″	59/64″	3/4″-14 NPT
23.5mm	.9252″
23.8125mm	.9375″	15/16″
24mm	.9449″		M27x3 coarse
24.2094mm	.953125″	61/64″
24.5mm	.9646″		M26x1.5 Fine
24.6063mm	.96875″	31/32″
25mm	.9843″		M27x2 Fine
25.0031mm	.984375″	63/64″	1-1/8″-7 UNC
25.4mm	1.000″	1″

 

 

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