M12×1.25 Thread Specifications
Complete dimensions for M12×1.25 fine pitch thread per ISO 724. Pitch: 1.25mm (20.3 TPI equivalent).
Thread Dimensions
| Designation | M12×1.25 |
| Thread Series | ISO Metric Fine |
| Pitch | 1.25 mm (20.3 TPI) |
| Major Diameter (d) | 12 mm (0.4724") |
| Pitch Diameter (d₂) | 11.1881 mm (0.4405") |
| Minor Diameter — External (d₁) | 10.4664 mm (0.4121") |
| Minor Diameter — Internal (D₁) | 10.6469 mm (0.4192") |
| Thread Depth | 0.6766 mm |
| Tensile Stress Area | 92.07 mm² |
| Fundamental Triangle Height (H) | 1.0825 mm |
Tap Drill Size
Recommended tap drill: 10.5 mm
Calculated minor diameter (D₁): 10.65 mm. Closest standard metric drill: 10.5 mm.
Closest inch drill: 27/64" (0.4219" / 10.72 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 20.7 | 36.8 |
| 4.8 | 310 | 420 | 28.5 | 38.7 |
| 5.8 | 380 | 520 | 35.0 | 47.9 |
| 8.8 | 580 | 800 | 53.4 | 73.7 |
| 9.8 | 650 | 900 | 59.8 | 82.9 |
| 10.9 | 830 | 1040 | 76.4 | 95.8 |
| 12.9 | 970 | 1220 | 89.3 | 112.3 |
Proof load = stress area × proof stress. Per ISO 898-1.
Related Thread Sizes
Common Applications
- Connecting rods
- Suspension components
- High-strength assemblies
- Precision equipment
How M12×1.25 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (12 mm) and pitch (1.25 mm):
- Fundamental triangle height: H = (√3/2) × P = 1.0825 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 11.1881 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 10.4664 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 10.6469 mm
- Thread depth: 5H/8 = 0.6766 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 92.07 mm²