Drill Bit Size Chart(Decimal, Fraction, MM & Letter Sizes)

Precision-focused, workshop-ready drill bit conversion chart for woodworkers, machinists, and DIYers. Compare number, letter, fractional, decimal, and metric sizes side by side and export print-perfect PDFs without signups.

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5 SystemsNumber · Letter · Fraction · Decimal · MM

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Workshop • 1/16 → 1/2 • A4

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Drill Bit Size Conversion Chart

Systems: Number, Fraction, Decimal, MM • Range 1/16 → 1/2 • A4

Number	Fraction	Decimal (in)	Millimeters
	1/16"	0.0625	1.59
#52		0.0635	1.61
#51		0.0670	1.70
#50		0.0700	1.78
#49		0.0730	1.85
#48		0.0760	1.93
	5/64"	0.0781	1.98
#47		0.0785	1.99
		0.0787	2.00
#46		0.0810	2.06
#45		0.0820	2.08
#44		0.0860	2.18
#43		0.0890	2.26
#42		0.0935	2.38
	3/32"	0.0938	2.38
#41		0.0960	2.44
#40		0.0980	2.49
		0.0984	2.50
#39		0.0995	2.53
#38		0.1015	2.58
#37		0.1040	2.64
#36		0.1065	2.71
	7/64"	0.1094	2.78
#35		0.1100	2.79
#34		0.1110	2.82
#33		0.1130	2.87
#32		0.1160	2.95
		0.1181	3.00
#31		0.1200	3.05
	1/8"	0.1250	3.17
#30		0.1285	3.26
#29		0.1360	3.45
		0.1378	3.50
#28		0.1405	3.57
	9/64"	0.1406	3.57
#27		0.1440	3.66
#26		0.1470	3.73
#25		0.1495	3.80
#24		0.1520	3.86
#23		0.1540	3.91
	5/32"	0.1563	3.97
#22		0.1570	3.99
		0.1575	4.00
#21		0.1590	4.04
#20		0.1610	4.09
#19		0.1660	4.22
#18		0.1695	4.30
	11/64"	0.1719	4.37
#17		0.1730	4.39
#16		0.1770	4.50
		0.1772	4.50
#15		0.1800	4.57
#14		0.1820	4.62
#13		0.1850	4.70
	3/16"	0.1875	4.76
#12		0.1890	4.80
#11		0.1910	4.85
#10		0.1935	4.92
#9		0.1960	4.98
		0.1969	5.00
#8		0.1990	5.05
#7		0.2010	5.11
	13/64"	0.2031	5.16
#6		0.2040	5.18
#5		0.2055	5.22
#4		0.2090	5.31
#3		0.2130	5.41
		0.2165	5.50
	7/32"	0.2188	5.56
#2		0.2210	5.61
#1		0.2280	5.79
		0.2340	5.94
	15/64"	0.2344	5.95
		0.2362	6.00
		0.2380	6.04
		0.2420	6.15
		0.2460	6.25
	1/4"	0.2500	6.35
		0.2559	6.50
		0.2570	6.53
		0.2610	6.63
	17/64"	0.2656	6.75
		0.2660	6.76
		0.2720	6.91
		0.2756	7.00
		0.2770	7.04
		0.2810	7.14
	9/32"	0.2813	7.14
		0.2900	7.37
		0.2950	7.49
		0.2953	7.50
	19/64"	0.2969	7.54
		0.3020	7.67
	5/16"	0.3125	7.94
		0.3150	8.00
		0.3160	8.03
		0.3230	8.20
	21/64"	0.3281	8.33
		0.3320	8.43
		0.3346	8.50
		0.3390	8.61
	11/32"	0.3438	8.73
		0.3480	8.84
		0.3543	9.00
		0.3580	9.09
	23/64"	0.3594	9.13
		0.3680	9.35
		0.3740	9.50
	3/8"	0.3750	9.53
		0.3770	9.58
		0.3860	9.80
	25/64"	0.3906	9.92
		0.3937	10.00
		0.3970	10.08
		0.4040	10.26
	13/32"	0.4063	10.32
		0.4130	10.49
		0.4134	10.50
	27/64"	0.4219	10.72
		0.4331	11.00
	7/16"	0.4375	11.11
		0.4528	11.50
	29/64"	0.4531	11.51
	15/32"	0.4688	11.91
		0.4724	12.00
	31/64"	0.4844	12.30
		0.4921	12.50
	1/2"	0.5000	12.70

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File Details

Rows

128

Range

1/16 → 1/2 • A4

PDF FILE SIZE

≈0KB

Quality

300 DPI

Wood Screw Pilot Hole Guide

Prevent split wood and stripped screws. Match your drill bit to the screw size and wood hardness.

Screw Size	Softwood Pilot (Pine, Cedar)	Hardwood Pilot (Oak, Maple)	Clearance Hole (Shank pass-through)
#4	1/16"	5/64"	1/8"
#6	5/64"	3/32"	9/64"
#8	3/32"	1/8"	11/64"
#10	7/64"	9/64"	3/16"
#12	1/8"	5/32"	7/32"
#14	9/64"	11/64"	1/4"

Which Drill Bit Type?

Selecting the right bit geometry for your material.

🌪️

Twist Bit

Wood, Metal, Plastic

The standard general-purpose bit. 118° or 135° point.

🪵

Brad Point

Wood Only

Precision tip prevents wandering. Clean entry/exit holes.

🧱

Masonry Bit

Brick, Concrete, Stone

Carbide tip. Must use with Hammer Drill mode.

⭕

Forstner Bit

Wood

Drills flat-bottomed holes. Great for hinges and large diameters.

How to Use This Drill Bit Chart

Move from stamped markings to the exact size you need, then export a print-ready PDF for the shop wall.

Read the markings

Check the shank for a number, letter, fraction, or metric stamp. When markings are worn, measure the diameter with calipers.

Find a clean match

Locate your value in the matching column, then read across to see the closest equivalents in every system.

Choose the right fit

Use tap-drill and pilot recommendations to avoid broken taps, stripped holes, or blown-out fibers in wood.

Common Applications

Practical guidance for the shop floor, job site, or garage.

🪵

Woodworking

Pick dowel, hinge, shelf-pin, and pilot hole sizes that prevent tear-out and splitting in hardwoods and sheet goods.

•Pilot holes that match screw core diameters
•Brad point and Forstner equivalents
•Common staples: 1/8", 3/16", 1/4"

⚙️

Metalworking & CNC

Match tap drills to thread specs, or swap between metric and imperial when tooling inventory is limited.

•#6-32, #8-32, #10-24 tap drills
•Metric substitutions with mm equivalents
•Fine-pitch and clearance hole reminders

🔨

DIY & Site Work

Pick the right bit for anchors, brackets, and cabinetry installs without guessing or over-drilling.

•Anchor and masonry pilot sizes
•Quick matches for pocket hole and jig sizes
•Laminate-friendly, ink-saving templates

Drill Bit Size Systems Explained

Understand how each sizing system is used so you can translate drawings, spec sheets, and on-tool markings effortlessly.

Smallest

Number Sizes (#1–#80)

Wire-gauge drill bits for precision work. Higher numbers are smaller; #80 is just 0.0135".

Bridge

Letter Sizes (A–Z)

Bridge the gap between number and fractional bits. Letter F (0.257") is a classic 5/16"-18 tap drill.

Everyday

Fractional Sizes (1/64"–1")

1/64" increments for woodworking and general construction with easy-to-read imperial notation.

Precision

Decimal & Metric

Engineering-friendly decimals with matching millimeters for CNC, CAD, and cross-border builds.

Tap Drill Selection Guide

Use the right pilot to protect your taps and threads. These favorites are baked into the chart’s tap-drill notes.

Thread Size	Threads / Inch	Tap Drill	Decimal (in)
6-32 UNC	32	#36	0.1065"
8-32 UNC	32	#29	0.1360"
10-24 UNC	24	#25	0.1495"
1/4"-20 UNC	20	#7	0.2010"
5/16"-18 UNC	18	Letter F	0.2570"

Tip: The chart also shows metric substitutions so you can keep projects moving even when the exact bit is missing.

Related Workshop Charts

Round out your shop wall set with these printables.

Fraction → DecimalEducational

Fraction	Decimal	Percent
1/64	0.0156	1.56%
1/32	0.0313	3.13%
1/16	0.0625	6.25%
1/8	0.1250	12.5%
3/16	0.1875	18.8%
1/4	0.2500	25%
5/16	0.3125	31.3%
3/8	0.3750	37.5%
1/2	0.5000	50%
3/4	0.7500	75%

Fraction to Decimal

Fractions from 1/64 to whole numbers for math education and precision cutting.

Special Education Workshop Engineering education math woodworking engineering

Customize & Download

MM → InchesPro template

Millimeters	Decimal (in)	Fraction (in)
0.5	0.020	0
1	0.039	1/16
6.35	0.250	1/4
12.7	0.500	1/2
19	0.748	3/4
25.4	1.000	1
38.1	1.500	1 1/2
50.8	2.000	2
76.2	3.000	3
101.6	4.000	4

MM to Inches Chart

Convert millimeters to inches with decimals and fractions for woodworking and engineering.

Length Workshop Engineering math engineering woodworking

Customize & Download

Inches → MMWorkshop preset

Inches (fraction)	Inches (decimal)	Millimeters	Centimeters
1/4"	0.250	6.35	0.64
1/2"	0.500	12.70	1.27
1"	1.000	25.40	2.54
1 1/2"	1.500	38.10	3.81
2"	2.000	50.80	5.08
2 1/2"	2.500	63.50	6.35
3"	3.000	76.20	7.62
4"	4.000	101.60	10.16
5"	5.000	127.00	12.70
6"	6.000	152.40	15.24

Inches to MM

Imperial to metric conversions for hardware sizing and fabrication.

Length Workshop Engineering hardware engineering

Customize & Download

CM → InchesSizing helper

Centimeters	Meters	Decimal (in)	Fraction (in)	ft'-in
5	0.05	1.97	1 15/16"	0'2"
10	0.10	3.94	3 15/16"	0'4"
20	0.20	7.87	7 7/8"	0'8"
30	0.30	11.81	11 13/16"	1'0"
50	0.50	19.69	19 11/16"	1'8"
70	0.70	27.56	27 9/16"	2'4"
90	0.90	35.43	35 7/16"	2'11"
100	1.00	39.37	39 3/8"	3'3"
130	1.30	51.18	51 3/16"	4'3"
180	1.80	70.87	70 7/8"	5'11"

CM to Inches Chart

Convert centimeters to inches with precision for international sizing and measurements.

Length Workshop Education shopping construction

Customize & Download

Explore more: Categories · Use Cases

Frequently Asked Questions

Straight answers for the most common workshop sizing questions.

Why are higher number drills smaller?

The number system is based on wire gauge—more drawing steps produce thinner wire and, by extension, smaller drill bits. #80 is tiny (0.0135") while #1 is larger (0.228"). Quick presets keep number, letter, and fractional columns aligned so you can see the step-downs at a glance.

What pilot hole size should I use for screws or anchors?

Match the pilot to the screw core, not the thread. Examples: #8 wood screw → 7/64" in hardwood or 3/32" in softwood; 1/4"-20 tap uses a #7 drill; plastic anchors call for the diameter printed on the package—the chart lists the common picks.

How do I convert between drill bit sizes and millimeters?

Turn on the decimal and mm columns, then read straight across. 1/4" becomes 0.2500 in and 6.35 mm; 5 mm lands near 13/64". No manual math required.

What tap drill should I use?

Enable "Show Tap Drill Notes" to display tap recommendations in the Notes column. Quick picks: #36 for 6-32, #29 for 8-32, #25 for 10-24, #7 for 1/4-20, Letter F for 5/16-18.

How do I export or print this drill bit chart?

Use Download PDF for a 300 DPI, watermark-free file, or Print Chart for direct printing. Download PNG lets you pick a page; Export PNG (ZIP) saves the full page range. Choose A4 or Letter to match your printer.

Can I substitute a close metric bit for an imperial size?

Yes for most wood projects; use the decimal/mm columns to check the gap. For tapped holes or precision fits, stay within a few thousandths of an inch or use the specified tap drill.

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