Metric fine
Tap drill 7.25 mm for a M8 × 0.75 thread — major Ø 8 mm, pitch 0.75 mm (33.87 TPI).
Profile
| Designation | M8 × 0.75 |
|---|---|
| Major (outside) diameter | 8 mm · 0.315" |
| Pitch | 0.75 mm · 33.87 TPI |
| Pitch diameter | 7.513 mm · 0.2958" |
| Minor diameter (external) | 7.08 mm · 0.2787" |
| Minor diameter (internal) | 7.188 mm · 0.283" |
| Recommended tap drill | 7.25 mm · ≈77% thread |
| Clearance hole | Close 8.4 · Normal 9 · Loose 10 mm |
| Hex head (across flats) | 13 mm |
| Socket key (across flats) | 6 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 | 41.8 mm² | 18.19 kN | 29.1 N·m |
| Class 10.9 | 41.8 mm² | 26.03 kN | 41.6 N·m |
| Class 12.9 | 41.8 mm² | 30.42 kN | 48.7 N·m |
For a M8 × 0.75 thread, drill the hole with a 7.25 mm tap drill (7.25 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 8 mm and a pitch of 0.75 mm (33.87 TPI).
To pass a M8 × 0.75 bolt through a part rather than thread it, use a clearance hole: Close 8.4 · Normal 9 · Loose 10 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.
Same diameter
Nearby sizes