M12 Screw Hole Size

M12 clearance hole (bolt passes through)

A clearance hole lets the M12 bolt’s 12 mm shank slide straight through without binding. The standard sizes (ISO 273):

When in doubt, 13.5 mm is the safe default. Need the same numbers for smaller sizes? The full table is in the metric clearance hole size chart, and the bolt-focused version is the bolt hole size chart.

M12 tapped hole (threading into the part)

To cut M12 threads directly into a part, you drill a smaller tap drill hole first, then run an M12 tap. For standard coarse M12 (1.75 mm pitch), the tap drill is 10.2 mm.

Tapping works in metal. In plastic and 3D prints, cut threads strip easily — at M12 the loads are usually high enough that a metal fastener and a clearance hole (bolt-and-nut) is the safer choice. For smaller threaded features in printed parts, see heat-set inserts for 3D printing and how to add threads to a part.

M12 holes for 3D printing

Printed holes come out smaller than designed — the plastic squeezes inward and the first layer can sag. For a 3D-printed M12 clearance hole, start one size up (around 13.8–14.0 mm modeled) and test-fit; widen if the bolt binds. The reasons and a general fit guide are in tolerances for 3D printed parts.

Designing the part that holds the hole? Mind the wall around it — see wall thickness for 3D printing.

Put an M12 hole in your part

With PartWork.ai you describe the part you need — “a base plate with four M12 clearance holes on a 100 mm bolt circle” — and get a solid part you can view free and export. No CAD skills. It runs in the browser on desktop or phone. See creating parts and exporting files.