M2 tap drill size

Drill a 1.6 mm hole (0.0630") for an M2 × 0.4 tap. That leaves about 77% thread, the standard for general-purpose tapping.

Tap drill
1.6 mm
0.0630" · 1.60 mm · 77% thread
Inch drill
1/16" 79% thread
Clearance (close)
2.2 mm
Heat-set insert hole
3.20 mm
Helicoil (STI) drill
2.1 mm
M2 tap drill: 1.6 mm (0.0630 in / 1.60 mm), 77% thread

M2 thread specs

SeriesISO metric coarse
Major diameter2.00 mm (0.0787")
Pitch0.4 mm (63.5 TPI)
Basic minor diameter1.57 mm (0.0617")
Common internal class6H

Every drill that works for M2

Drills from all four sets that give 50–85% thread, largest first. Lower percentages tap easier; see how much thread you need.

DrillThreadinmmSetGood for
#5157%0.06701.70Numberdeep holes only
1.7 mm58%0.06691.70Metricdeep holes only
1.65 mm67%0.06501.65Metrichard or tough metals
#5274%0.06351.61Numbergeneral use
1.6 mmstandard77%0.06301.60Metricgeneral use
1/16"79%0.06251.59Fractionalgeneral use

M2 clearance hole

The hole a M2 screw passes through. ISO 273 fine, medium and coarse series.

Fitmmin
Close (fine)2.2 mm0.0866
Normal (medium)2.4 mm0.0945
Loose (coarse)2.6 mm0.1024

M2 counterbore and countersink

For a socket head cap screw to sit flush, and for a flat head socket screw.

Socket head counterboreDiameterDepth
AMES4.40 mm2.00 mm

ISO 10642 flat head socket screws start at M3, so there is no standard countersink for M2.

M2 heat-set insert hole

Hole to model for a brass heat-set insert in a 3D print. Brands size their knurl differently, so use your brand’s number.

BrandHoleInsert lengthMin. wall
CNC Kitchen3.20 mm––
ruthex3.20 mm4 mm1.3 mm
Generic (Albany County)3.20 mm––

M2 holes in a 3D print

Printed holes usually come out undersize. Model the hole at the drill size plus what your printer loses, then tap or drill to size. Why printed holes shrink.

Print a test hole, measure it with calipers, enter the difference. 0 models the nominal size.

Hole to tap
1.60 mm
Clearance hole
2.20 mm
Heat-set insert
3.20 mm

M2 thread repair (Helicoil)

Stripped M2 thread? Drill out with the STI drill, tap with a M2 × 0.4 STI tap, and fit a wire thread insert. The drill in your repair kit’s instructions wins over any chart.

ChartSTI drillinmm
MISUMI2.1 mm0.08272.10

Related sizes

M2.5next size upFull chartmetric coarse

Frequently asked questions

What size drill do I use for an M2 tap?
Use a 1.6 mm (1.60 mm / 0.0630 in) drill. It leaves about 77% thread, the standard for general-purpose tapping.
What inch drill can I use for an M2 tap?
1/16" (1.59 mm / 0.0625 in) is the closest, giving about 79% thread. Anything from about 65% to 80% thread taps well in most materials.
What size clearance hole for an M2 screw?
2.2 mm (2.20 mm) for a close fit, 2.4 mm (2.40 mm) for a normal fit.
What hole size for an M2 heat-set insert?
3.2 mm in the brands listed here. Check your insert's own listing; the hole is sized for that insert's knurl.

Sources

Spotted a wrong number? Email contact@clove3d.com and it gets fixed.

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% thread = (major − drill) ÷ (1.299 × pitch) × 100. The standard drill comes from published charts and is checked against this formula on every build.