M8×0.75 Thread Specifications
Complete dimensions for M8×0.75 fine pitch thread per ISO 724. Pitch: 0.75mm (33.9 TPI equivalent).
Thread Dimensions
| Designation | M8×0.75 |
| Thread Series | ISO Metric Fine |
| Pitch | 0.75 mm (33.9 TPI) |
| Major Diameter (d) | 8 mm (0.315") |
| Pitch Diameter (d₂) | 7.5129 mm (0.2958") |
| Minor Diameter — External (d₁) | 7.0798 mm (0.2787") |
| Minor Diameter — Internal (D₁) | 7.1881 mm (0.283") |
| Thread Depth | 0.4059 mm |
| Tensile Stress Area | 41.19 mm² |
| Fundamental Triangle Height (H) | 0.6495 mm |
Tap Drill Size
Recommended tap drill: 7.0 mm
Calculated minor diameter (D₁): 7.19 mm. Closest standard metric drill: 7.0 mm.
Closest inch drill: 9/32" (0.2812" / 7.14 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 9.3 | 16.5 |
| 4.8 | 310 | 420 | 12.8 | 17.3 |
| 5.8 | 380 | 520 | 15.7 | 21.4 |
| 8.8 | 580 | 800 | 23.9 | 33.0 |
| 9.8 | 650 | 900 | 26.8 | 37.1 |
| 10.9 | 830 | 1040 | 34.2 | 42.8 |
| 12.9 | 970 | 1220 | 40.0 | 50.3 |
Proof load = stress area × proof stress. Per ISO 898-1.
Related Thread Sizes
Common Applications
- Automotive engine components
- Precision machinery
- Vibration-prone joints
- Cylinder head bolts
How M8×0.75 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (8 mm) and pitch (0.75 mm):
- Fundamental triangle height: H = (√3/2) × P = 0.6495 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 7.5129 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 7.0798 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 7.1881 mm
- Thread depth: 5H/8 = 0.4059 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 41.19 mm²