M16 thread: tap drill, clearance hole and counterbore sizes
The hole sizes and depths for an M16 coarse thread, and how to put it on a drawing.
| Property | Value |
|---|---|
| Nominal diameter | 16 mm |
| Pitch (coarse) | 2 mm |
| Tap drill | Ø14 mm |
| Clearance hole, fine | Ø17 mm |
| Clearance hole, medium | Ø17.5 mm |
| Clearance hole, coarse | Ø18.5 mm |
| Socket head cap screw head Ø (ISO 4762) | 24 mm |
| Counterbore Ø (DIN 974-1) | 26 mm |
| Counterbore depth (head flush) | about 16.5 mm |
Thread depth
| Material | Full thread engagement |
|---|---|
| Steel, stainless steel | 16–24 mm |
| Aluminium, brass | 24–32 mm |
| Plastics | 32–40 mm or an insert |
Drill the tap hole at least 6–8 mm (3–4 pitches) deeper than the full thread, plus the drill point. More on this in how deep a tapped thread should be.
How to call it out on a drawing
Tapped blind hole: M16x2-6H, thread 24 deep, tap drill Ø14 32 deep.
Clearance hole with counterbore: Ø17.5 through, counterbore Ø26 × 16.5 deep.
M14 | M20 | All thread sizes
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