What size is a 9/16" drill bit?

A 9/16" drill bit is 0.5625 in in diameter, which is 14.287 mm. It is the 9/16 in fractional size.

What is the metric equivalent of a 9/16" drill bit?

The closest metric drill to a 9/16" drill bit (14.287 mm) is 14.25 mm, which is 14.250 mm — 0.0015 in smaller.

What bolt fits through a 9/16" drill bit hole?

A hole drilled with a 9/16" drill bit is the standard normal clearance hole for 1/2"-28 UNEF, and a clearance hole for 2 other fastener sizes listed on this page.

Fractional drill · 9/16

9/16" Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes

https://shopmath.org/drills/fractional/9-16 · data verified August 1, 2026

A 9/16" drill bit is 0.5625 in (14.287 mm) in diameter. Diameters are nominal.

Series: Fractional
Designation: 9/16
Inch: 0.5625
mm: 14.287
Standard: ANSI/ASME B94.11M

Fractional Drill · 9/16 · nominal diameter

0.5625 in

Millimetre: 14.287mm
Fraction: 9/16in

Nominal diameter. A worn or run-out drill cuts oversize, which leaves less thread in a tapped hole than the table says.

9/16" Drill Bit Size in Inches and Millimetres

The nominal diameter of a 9/16" drill bit. Drill sizes are nominal — a worn drill, run-out or a soft material that closes in behind the cut all move the finished hole.

9/16" drill bit — decimal inch and millimetre diameter
Property	Value
Diameter, decimal inch	0.5625 in
Diameter, millimetre	14.287 mm
Fraction	9/16 in
Cross-sectional area	0.24850 in²

1 in = 25.4 mm exactly, so the two columns are the same value in different units, not two measurements.

Threads a 9/16" Drill Bit Taps

Every thread in this reference whose tap drill is the 9/16" drill bit, and the thread engagement it leaves. The engagement asked for and the engagement the drill actually produces are different numbers — that gap is why both columns are here.

Threads tapped with a 9/16" drill bit, by thread engagement
Thread	Series	Thread % asked for	Thread % this drill leaves
5/8"-18 UNF	Unified Fine (UNF)	80%	86.6
5/8"-18 UNF	Unified Fine (UNF)	85%	86.6
5/8"-11 UNC	Unified Coarse (UNC)	50%	52.9

Values are for cut taps. Rows marked default are the shop-default engagement for that thread.

Fasteners That Pass Through a 9/16" Drill Bit Hole

A hole drilled with a 9/16" drill bit is the standard clearance hole for these fasteners — the through-hole the bolt passes freely, not the tapped hole.

Fasteners whose clearance hole is drilled with a 9/16" drill bit
Fastener	Series	Clearance class
1/2"-28 UNEF	Unified Extra Fine (UNEF)	normal
1/2"-20 UNF	Unified Fine (UNF)	normal
1/2"-13 UNC	Unified Coarse (UNC)	normal

Clearance classes per ISO 273 (metric) and ASME B18.2.8 (inch): close for located joints, normal for general assembly, loose for slotted or adjustable joints.

9/16" Drill Bit Equivalents in Every Other Drill Series

The closest size to the 9/16" drill bit in each of the other three indexes, with the difference in inches. None of them is the same drill — check the difference before substituting one into a tapped hole.

Nearest number, letter, fractional and metric equivalents to a 9/16" drill bit
Property	Property	Diameter		Property
Drill	Series	in	mm	Difference, in
#1	Number	0.2280	5.791	−0.3345
Z	Letter	0.4130	10.490	−0.1495
14.25 mm	Metric	0.5610	14.250	−0.0015

A positive difference means the equivalent drill is larger, which leaves less thread in a tapped hole. Sizes without a link are stored for the nearest-drill calculation but do not carry their own page.

Drill Sizes Either Side of the 9/16" Drill Bit

Ordered by diameter across all four indexes, so the next size up may be a letter, a fraction or a metric drill rather than the next one in this series.

Standard drill sizes adjacent to a 9/16" drill bit, by diameter
Property	Property	Diameter
Drill	Series	in	mm
14 mm	Metric	0.5512	14.000
14.25 mm	Metric	0.5610	14.250
9/16"	Fractional	0.5625	14.287
14.5 mm	Metric	0.5709	14.500
37/64"	Fractional	0.5781	14.684

Sources and Method for the 9/16" Drill Bit Size

Drill diametercomputed

Number/letter: bd_warehouse drill_sizes.csv (Apache-2.0) cross-checked against Wikipedia Drill bit sizes (CC BY-SA 4.0). Fractional: computed 1/64 in steps per ANSI B94.11M. Metric: computed BS 328 increment pattern.

Verified against Wikipedia Drill bit sizes (CC BY-SA 4.0); 31/31 checks passed

Computed from the standard's formulas, then checked against published tables.

Tap drill usagecomputed+compiled

bd_warehouse drill_sizes.csv (Apache-2.0) + Wikipedia Drill bit sizes (CC BY-SA 4.0); fractional and metric computed from ANSI B94.11M / BS 328 increment patterns

Verified against drills: 31 checks passed across 1 harness(es)

Part computed from the standard's formulas, part compiled from agreeing public sources.

Formula

Fractional drill diameter

Ø  =  9/16 in  =  0.5625 in

Fractional drills are exact fractions of an inch in 1/64 in steps; the decimal is the fraction evaluated, not a measurement.

Assumptions

Diameters are nominal. Drill manufacturing tolerance, wear and run-out all cut oversize, and every one of those moves a tapped hole toward less thread than the table says.
Dataset scope: Number sizes #61-#80 are stored but tagged demandTier 'extended' — query-space-map.md Appendix A found the tail thinning in the 60s. Sizes below #80 and metric sizes above 25.0 mm excluded.

Data last verified

August 1, 2026

How this data is built and checked →

How to Cite This 9/16" Drill Bit Reference

Citation

ShopMath. "9/16" Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes." ShopMath, verified August 1, 2026, https://shopmath.org/drills/fractional/9-16

BibTeX

@misc{shopmath-drills-fractional-9-16,
  title        = {9/16" Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/drills/fractional/9-16}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/drills/fractional/9-16

Common Questions About the 9/16" Drill Bit

What size is a 9/16" drill bit?: A 9/16" drill bit is 0.5625 in in diameter, which is 14.287 mm. It is the 9/16 in fractional size.
What is the metric equivalent of a 9/16" drill bit?: The closest metric drill to a 9/16" drill bit (14.287 mm) is 14.25 mm, which is 14.250 mm — 0.0015 in smaller.
What bolt fits through a 9/16" drill bit hole?: A hole drilled with a 9/16" drill bit is the standard normal clearance hole for 1/2"-28 UNEF, and a clearance hole for 2 other fastener sizes listed on this page.

All fractional drill sizes · Complete drill size chart · Every drill series