M10×1.25 Thread Specifications
Complete dimensions for M10×1.25 fine pitch thread per ISO 724. Pitch: 1.25mm (20.3 TPI equivalent).
Thread Dimensions
| Designation | M10×1.25 |
| Thread Series | ISO Metric Fine |
| Pitch | 1.25 mm (20.3 TPI) |
| Major Diameter (d) | 10 mm (0.3937") |
| Pitch Diameter (d₂) | 9.1881 mm (0.3617") |
| Minor Diameter — External (d₁) | 8.4664 mm (0.3333") |
| Minor Diameter — Internal (D₁) | 8.6469 mm (0.3404") |
| Thread Depth | 0.6766 mm |
| Tensile Stress Area | 61.2 mm² |
| Fundamental Triangle Height (H) | 1.0825 mm |
Tap Drill Size
Recommended tap drill: 8.5 mm
Calculated minor diameter (D₁): 8.65 mm. Closest standard metric drill: 8.5 mm.
Closest inch drill: R (0.339" / 8.61 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 13.8 | 24.5 |
| 4.8 | 310 | 420 | 19.0 | 25.7 |
| 5.8 | 380 | 520 | 23.3 | 31.8 |
| 8.8 | 580 | 800 | 35.5 | 49.0 |
| 9.8 | 650 | 900 | 39.8 | 55.1 |
| 10.9 | 830 | 1040 | 50.8 | 63.6 |
| 12.9 | 970 | 1220 | 59.4 | 74.7 |
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 M10×1.25 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (10 mm) and pitch (1.25 mm):
- Fundamental triangle height: H = (√3/2) × P = 1.0825 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 9.1881 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 8.4664 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 8.6469 mm
- Thread depth: 5H/8 = 0.6766 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 61.2 mm²