M10 tap drill size

Drill a 8.5 mm hole (0.3346") for an M10 × 1.5 tap. That leaves about 77% thread, the standard for general-purpose tapping.

Tap drill
8.5 mm
0.3346" · 8.50 mm · 77% thread
Inch drill
Q 80% thread
Clearance (close)
10.5 mm
Helicoil (STI) drill
10.3 mm
M10 tap drill: 8.5 mm (0.3346 in / 8.50 mm), 77% thread

M10 thread specs

SeriesISO metric coarse
Major diameter10.00 mm (0.3937")
Pitch1.5 mm (16.9 TPI)
Basic minor diameter8.38 mm (0.3298")
Common internal class6H

Every drill that works for M10

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

DrillThreadinmmSetGood for
9.0 mm51%0.35439.00Metricdeep holes only
8.9 mm56%0.35048.90Metricdeep holes only
S60%0.34808.84Letterdeep holes only
8.8 mm62%0.34658.80Metrichard or tough metals
11/32"65%0.34388.73Fractionalhard or tough metals
8.7 mm67%0.34258.70Metrichard or tough metals
R71%0.33908.61Lettergeneral use
8.6 mm72%0.33868.60Metricgeneral use
8.5 mmstandard77%0.33468.50Metricgeneral use
Q80%0.33208.43Lettermore torque, more broken taps
8.4 mm82%0.33078.40Metricmore torque, more broken taps

M10 clearance hole

The hole a M10 screw passes through. ISO 273 fine, medium and coarse series.

Fitmmin
Close (fine)10.5 mm0.4134
Normal (medium)11.0 mm0.4331
Loose (coarse)12.0 mm0.4724

M10 counterbore and countersink

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

Socket head counterboreDiameterDepth
NBK17.50 mm10.80 mm
AMES17.25 mm10.00 mm

Flat head socket screw: countersink at 90° (metric screws, ISO 10642) to 22.40 mm (0.8819") across for a flush head. Inch flat heads use 82°, so don't mix countersinks.

M10 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
8.50 mm
Clearance hole
10.50 mm

M10 thread repair (Helicoil)

Stripped M10 thread? Drill out with the STI drill, tap with a M10 × 1.5 STI tap, and fit a wire thread insert. The drill in your repair kit’s instructions wins over any chart.

ChartSTI drillinmm
MISUMI10.3 mm0.405510.30

Related sizes

M8next size downM12next size up3/8-16closest inchFull chartmetric coarse

Frequently asked questions

What size drill do I use for an M10 tap?
Use a 8.5 mm (8.50 mm / 0.3346 in) drill. It leaves about 77% thread, the standard for general-purpose tapping.
What inch drill can I use for an M10 tap?
Q (8.43 mm / 0.3320 in) is the closest, giving about 80% thread. Anything from about 65% to 80% thread taps well in most materials.
What size clearance hole for an M10 screw?
10.5 mm (10.50 mm) for a close fit, 11.0 mm (11.00 mm) for a normal fit.
What is the inch equivalent of M10?
3/8-16 is the closest size (9.52 mm vs 10.00 mm major diameter). The pitches differ, so the screws and tapped holes are not interchangeable.

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.