What size is a 7 mm drill bit?

A 7 mm drill bit is 0.2756 in in diameter, which is 7.000 mm.

What thread does a 7 mm drill bit tap?

A 7 mm drill bit is the tap drill for M8×1 at 75% requested thread engagement, where it leaves 77.0% thread with a cut tap.

What fraction is a 7 mm drill bit closest to?

A 7 mm drill bit (0.2756 in) sits closest to the 9/32" fractional drill at 0.2813 in, a difference of 0.0057 in.

Metric drill · 7 mm

7 mm Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes

https://shopmath.org/drills/metric/7mm · data verified August 1, 2026

A 7 mm drill bit is 0.2756 in (7.000 mm) in diameter. It is the tap drill for M8×1 at 75% thread engagement with a cut tap, where it leaves 77.0% thread. The nearest fractional size is 9/32" at 0.2813 in. Diameters are nominal.

Series: Metric
Designation: 7 mm
Inch: 0.2756
mm: 7.000
Standard: ANSI/ASME B94.11M

Metric Drill · 7 mm · nominal diameter

0.2756 in

Millimetre: 7.000mm
Taps: M8×1

Nominal diameter. As a tap drill it leaves 77.0% thread in M8×1 with a cut tap.

7 mm Drill Bit Size in Inches and Millimetres

The nominal diameter of a 7 mm 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.

7 mm drill bit — decimal inch and millimetre diameter
Property	Value
Diameter, decimal inch	0.2756 in
Diameter, millimetre	7.000 mm
Cross-sectional area	0.05965 in²

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

Threads a 7 mm Drill Bit Taps

Every thread in this reference whose tap drill is the 7 mm 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 7 mm drill bit, by thread engagement
Thread	Series	Thread % asked for	Thread % this drill leaves
M8×1	ISO Metric Fine	75%default	77.0
M8×1	ISO Metric Fine	80%	77.0
M8×1.25	ISO Metric Coarse	60%	61.6

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

7 mm Drill Bit Equivalents in Every Other Drill Series

The closest size to the 7 mm 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 7 mm drill bit
Property	Property	Diameter		Property
Drill	Series	in	mm	Difference, in
#1	Number	0.2280	5.791	−0.0476
J	Letter	0.2770	7.036	+0.0014
9/32"	Fractional	0.2813	7.144	+0.0057

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 7 mm 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 7 mm drill bit, by diameter
Property	Property	Diameter
Drill	Series	in	mm
6.9 mm	Metric	0.2717	6.900
I	Letter	0.2720	6.909
7 mm	Metric	0.2756	7.000
J	Letter	0.2770	7.036
7.1 mm	Metric	0.2795	7.100

Sources and Method for the 7 mm 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.

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. M8×1 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 7 mm Drill Bit Reference

Citation

ShopMath. "7 mm Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes." ShopMath, verified August 1, 2026, https://shopmath.org/drills/metric/7mm

BibTeX

@misc{shopmath-drills-metric-7mm,
  title        = {7 mm Drill Bit Size — Decimal Inch, Millimetre and Tap Sizes},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/drills/metric/7mm}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/drills/metric/7mm

Common Questions About the 7 mm Drill Bit

What size is a 7 mm drill bit?: A 7 mm drill bit is 0.2756 in in diameter, which is 7.000 mm.
What thread does a 7 mm drill bit tap?: A 7 mm drill bit is the tap drill for M8×1 at 75% requested thread engagement, where it leaves 77.0% thread with a cut tap.
What fraction is a 7 mm drill bit closest to?: A 7 mm drill bit (0.2756 in) sits closest to the 9/32" fractional drill at 0.2813 in, a difference of 0.0057 in.

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