M4 tap drill size

Drill a 3.3 mm hole (0.1299") for an M4 × 0.7 tap. That leaves about 77% thread, the standard for general-purpose tapping.

Tap drill
3.3 mm
0.1299" · 3.30 mm · 77% thread
Inch drill
#30 81% thread
Clearance (close)
4.3 mm
Heat-set insert hole
5.60 mm
Helicoil (STI) drill
4.1 mm
M4 tap drill: 3.3 mm (0.1299 in / 3.30 mm), 77% thread

M4 thread specs

SeriesISO metric coarse
Major diameter4.00 mm (0.1575")
Pitch0.7 mm (36.3 TPI)
Basic minor diameter3.24 mm (0.1276")
Common internal class6H

Every drill that works for M4

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

DrillThreadinmmSetGood for
3.5 mm55%0.13783.50Metricdeep holes only
#2960%0.13603.45Numberhard or tough metals
3.4 mm66%0.13393.40Metrichard or tough metals
3.3 mmstandard77%0.12993.30Metricgeneral use
#3081%0.12853.26Numbermore torque, more broken taps

M4 clearance hole

The hole a M4 screw passes through. ISO 273 fine, medium and coarse series.

Fitmmin
Close (fine)4.3 mm0.1693
Normal (medium)4.5 mm0.1772
Loose (coarse)4.8 mm0.1890

M4 counterbore and countersink

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

Socket head counterboreDiameterDepth
NBK8.00 mm4.40 mm
AMES8.25 mm4.00 mm

Flat head socket screw: countersink at 90° (metric screws, ISO 10642) to 8.96 mm (0.3528") across for a flush head. Inch flat heads use 82°, so don't mix countersinks.

M4 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 Kitchen5.60 mm––
ruthex5.60 mm8.1 mm2.1 mm
Accu5.60 mm––
Generic (Albany County)5.30 mm––

M4 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
3.30 mm
Clearance hole
4.30 mm
Heat-set insert
5.60 mm

M4 thread repair (Helicoil)

Stripped M4 thread? Drill out with the STI drill, tap with a M4 × 0.7 STI tap, and fit a wire thread insert. The drill in your repair kit’s instructions wins over any chart.

ChartSTI drillinmm
MISUMI4.1 mm0.16144.10

Related sizes

M3next size downM5next size up8-32closest inchFull chartmetric coarse

Frequently asked questions

What size drill do I use for an M4 tap?
Use a 3.3 mm (3.30 mm / 0.1299 in) drill. It leaves about 77% thread, the standard for general-purpose tapping.
What inch drill can I use for an M4 tap?
#30 (3.26 mm / 0.1285 in) is the closest, giving about 81% thread. Anything from about 65% to 80% thread taps well in most materials.
What size clearance hole for an M4 screw?
4.3 mm (4.30 mm) for a close fit, 4.5 mm (4.50 mm) for a normal fit.
What hole size for an M4 heat-set insert?
Between 5.3 mm and 5.6 mm depending on the brand: CNC Kitchen 5.6 mm, ruthex 5.6 mm, Accu 5.6 mm, Generic (Albany County) 5.3 mm. Use your insert's own number.
What is the inch equivalent of M4?
8-32 is the closest size (4.17 mm vs 4.00 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.

Other clove3d tools

Steps per mm calculatorsteps/mm for leadscrews, belts and rack & pinion, with GRBL & Marlin lines.Feeds & speeds calculatorSpindle RPM and feed rate from surface speed, tool diameter and chip load.Belt tension calculatorTension GT2 / GT3 belts by plucking the span, frequency to tension either way.Lathe RPM calculatorOptimal spindle speed from workpiece diameter, material and tool type (HSS or carbide).Lathe motor power calculatorHow much motor power you need for a turning job, from cutting speed, depth and feed.

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