Metric fine
Tap drill 8.75 mm for a M10 × 1.25 thread — major Ø 10 mm, pitch 1.25 mm (20.32 TPI).
Profile
| Designation | M10 × 1.25 |
|---|---|
| Major (outside) diameter | 10 mm · 0.3937" |
| Pitch | 1.25 mm · 20.32 TPI |
| Pitch diameter | 9.188 mm · 0.3617" |
| Minor diameter (external) | 8.466 mm · 0.3333" |
| Minor diameter (internal) | 8.647 mm · 0.3404" |
| Recommended tap drill | 8.75 mm · ≈77% thread |
| Clearance hole | Close 10.5 · Normal 11 · Loose 12 mm |
| Hex head (across flats) | 16 mm |
| Socket key (across flats) | 8 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 | 61.2 mm² | 26.62 kN | 53.2 N·m |
| Class 10.9 | 61.2 mm² | 38.1 kN | 76.2 N·m |
| Class 12.9 | 61.2 mm² | 44.52 kN | 89 N·m |
For a M10 × 1.25 thread, drill the hole with a 8.75 mm tap drill (8.75 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 10 mm and a pitch of 1.25 mm (20.32 TPI).
To pass a M10 × 1.25 bolt through a part rather than thread it, use a clearance hole: Close 10.5 · Normal 11 · Loose 12 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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