Metric coarse
Tap drill 10.25 mm for a M12 × 1.75 thread — major Ø 12 mm, pitch 1.75 mm (14.51 TPI).
Profile
| Designation | M12 × 1.75 |
|---|---|
| Major (outside) diameter | 12 mm · 0.4724" |
| Pitch | 1.75 mm · 14.51 TPI |
| Pitch diameter | 10.863 mm · 0.4277" |
| Minor diameter (external) | 9.853 mm · 0.3879" |
| Minor diameter (internal) | 10.106 mm · 0.3979" |
| Recommended tap drill | 10.25 mm · ≈77% thread |
| Clearance hole | Close 13 · Normal 13.5 · Loose 14.5 mm |
| Hex head (across flats) | 18 mm |
| Socket key (across flats) | 10 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 | 84.3 mm² | 36.66 kN | 88 N·m |
| Class 10.9 | 84.3 mm² | 52.46 kN | 125.9 N·m |
| Class 12.9 | 84.3 mm² | 61.3 kN | 147.1 N·m |
For a M12 × 1.75 thread, drill the hole with a 10.25 mm tap drill (10.25 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 12 mm and a pitch of 1.75 mm (14.51 TPI).
To pass a M12 × 1.75 bolt through a part rather than thread it, use a clearance hole: Close 13 · Normal 13.5 · Loose 14.5 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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