Metric fine
Tap drill 15 mm for a M16 × 1.0 thread — major Ø 16 mm, pitch 1 mm (25.4 TPI).
Profile
| Designation | M16 × 1.0 |
|---|---|
| Major (outside) diameter | 16 mm · 0.6299" |
| Pitch | 1 mm · 25.4 TPI |
| Pitch diameter | 15.351 mm · 0.6044" |
| Minor diameter (external) | 14.773 mm · 0.5816" |
| Minor diameter (internal) | 14.918 mm · 0.5873" |
| Recommended tap drill | 15 mm · ≈77% thread |
| Clearance hole | Close 17 · Normal 17.5 · Loose 18.5 mm |
| Hex head (across flats) | 24 mm |
| Socket key (across flats) | 14 mm |
ISO 273 clearance holes (fine / medium / coarse).
Target preload is 75% of proof load; torque is estimated from T = K · F · d.
| Grade / class | Stress area | Preload | Torque |
|---|---|---|---|
| Class 8.8 | 178.2 mm² | 77.51 kN | 248 N·m |
| Class 10.9 | 178.2 mm² | 110.91 kN | 354.9 N·m |
| Class 12.9 | 178.2 mm² | 129.62 kN | 414.8 N·m |
For a M16 × 1.0 thread, drill the hole with a 15 mm tap drill (15 mm — the standard D − P rule) before tapping. That produces roughly 77% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 16 mm and a pitch of 1 mm (25.4 TPI).
To pass a M16 × 1.0 bolt through a part rather than thread it, use a clearance hole: Close 17 · Normal 17.5 · Loose 18.5 mm.
All values are generated from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables — not hand-entered. See the full reference.
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