What size is a 17/32" drill bit?

A 17/32" drill bit is 0.5313 in in diameter, which is 13.494 mm. It is the 17/32 in fractional size.

What thread does a 17/32" drill bit tap?

A 17/32" drill bit is the tap drill for 5/8"-11 UNC at 75% requested thread engagement, where it leaves 79.4% thread with a cut tap.

What is the metric equivalent of a 17/32" drill bit?

The closest metric drill to a 17/32" drill bit (13.494 mm) is 13.5 mm, which is 13.500 mm — 0.0002 in larger.

What bolt fits through a 17/32" drill bit hole?

A hole drilled with a 17/32" drill bit is the standard close clearance hole for 1/2"-28 UNEF, and a clearance hole for 2 other fastener sizes listed on this page.

Fractional drill · 17/32

17/32" Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes

https://shopmath.org/drills/fractional/17-32 · data verified August 1, 2026

A 17/32" drill bit is 0.5313 in (13.494 mm) in diameter. It is the tap drill for 5/8"-11 UNC at 75% thread engagement with a cut tap, where it leaves 79.4% thread. Diameters are nominal.

Series: Fractional
Designation: 17/32
Inch: 0.5313
mm: 13.494
Standard: ANSI/ASME B94.11M

Fractional Drill · 17/32 · nominal diameter

0.5313 in

Millimetre: 13.494mm
Fraction: 17/32in
Taps: 5/8"-11 UNC

Nominal diameter. As a tap drill it leaves 79.4% thread in 5/8"-11 UNC with a cut tap.

17/32" Drill Bit Size in Inches and Millimetres

The nominal diameter of a 17/32" 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.

17/32" drill bit — decimal inch and millimetre diameter
Property	Value
Diameter, decimal inch	0.5313 in
Diameter, millimetre	13.494 mm
Fraction	17/32 in
Cross-sectional area	0.22166 in²

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

Threads a 17/32" Drill Bit Taps

Every thread in this reference whose tap drill is the 17/32" 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 17/32" drill bit, by thread engagement
Thread	Series	Thread % asked for	Thread % this drill leaves
5/8"-11 UNC	Unified Coarse (UNC)	75%default	79.4
9/16"-24 UNEF	Unified Extra Fine (UNEF)	50%	57.7
9/16"-24 UNEF	Unified Extra Fine (UNEF)	60%	57.7
9/16"-24 UNEF	Unified Extra Fine (UNEF)	65%	57.7
9/16"-24 UNEF	Unified Extra Fine (UNEF)	70%	57.7
9/16"-18 UNF	Unified Fine (UNF)	50%	43.3
5/8"-11 UNC	Unified Coarse (UNC)	80%	79.4
5/8"-11 UNC	Unified Coarse (UNC)	85%	79.4

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

Fasteners That Pass Through a 17/32" Drill Bit Hole

A hole drilled with a 17/32" 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 17/32" drill bit
Fastener	Series	Clearance class
1/2"-28 UNEF	Unified Extra Fine (UNEF)	close
1/2"-20 UNF	Unified Fine (UNF)	close
1/2"-13 UNC	Unified Coarse (UNC)	close

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.

17/32" Drill Bit Equivalents in Every Other Drill Series

The closest size to the 17/32" 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 17/32" drill bit
Property	Property	Diameter		Property
Drill	Series	in	mm	Difference, in
#1	Number	0.2280	5.791	−0.3033
Z	Letter	0.4130	10.490	−0.1183
13.5 mm	Metric	0.5315	13.500	+0.0002

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 17/32" 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 17/32" drill bit, by diameter
Property	Property	Diameter
Drill	Series	in	mm
13.3 mm	Metric	0.5236	13.300
13.4 mm	Metric	0.5276	13.400
17/32"	Fractional	0.5313	13.494
13.5 mm	Metric	0.5315	13.500
13.6 mm	Metric	0.5354	13.600

Sources and Method for the 17/32" 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  =  17/32 in  =  0.5313 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.
Tap drill usage assumes cut taps. 5/8"-11 UNC at 75% requested engagement is what this drill is normally bought for.
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 17/32" Drill Bit Reference

Citation

ShopMath. "17/32" Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes." ShopMath, verified August 1, 2026, https://shopmath.org/drills/fractional/17-32

BibTeX

@misc{shopmath-drills-fractional-17-32,
  title        = {17/32" Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/drills/fractional/17-32}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/drills/fractional/17-32

Common Questions About the 17/32" Drill Bit

What size is a 17/32" drill bit?: A 17/32" drill bit is 0.5313 in in diameter, which is 13.494 mm. It is the 17/32 in fractional size.
What thread does a 17/32" drill bit tap?: A 17/32" drill bit is the tap drill for 5/8"-11 UNC at 75% requested thread engagement, where it leaves 79.4% thread with a cut tap.
What is the metric equivalent of a 17/32" drill bit?: The closest metric drill to a 17/32" drill bit (13.494 mm) is 13.5 mm, which is 13.500 mm — 0.0002 in larger.
What bolt fits through a 17/32" drill bit hole?: A hole drilled with a 17/32" drill bit is the standard close clearance hole for 1/2"-28 UNEF, and a clearance hole for 2 other fastener sizes listed on this page.

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