M16×1.25 Thread Specifications
Complete dimensions for M16×1.25 fine pitch thread per ISO 724. Pitch: 1.25mm (20.3 TPI equivalent).
Thread Dimensions
| Designation | M16×1.25 |
| Thread Series | ISO Metric Fine |
| Pitch | 1.25 mm (20.3 TPI) |
| Major Diameter (d) | 16 mm (0.6299") |
| Pitch Diameter (d₂) | 15.1881 mm (0.598") |
| Minor Diameter — External (d₁) | 14.4664 mm (0.5695") |
| Minor Diameter — Internal (D₁) | 14.6469 mm (0.5766") |
| Thread Depth | 0.6766 mm |
| Tensile Stress Area | 170.57 mm² |
| Fundamental Triangle Height (H) | 1.0825 mm |
Tap Drill Size
Recommended tap drill: 14.5 mm
Calculated minor diameter (D₁): 14.65 mm. Closest standard metric drill: 14.5 mm.
Closest inch drill: 37/64" (0.5781" / 14.68 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 38.4 | 68.2 |
| 4.8 | 310 | 420 | 52.9 | 71.6 |
| 5.8 | 380 | 520 | 64.8 | 88.7 |
| 8.8 | 580 | 800 | 98.9 | 136.5 |
| 9.8 | 650 | 900 | 110.9 | 153.5 |
| 10.9 | 830 | 1040 | 141.6 | 177.4 |
| 12.9 | 970 | 1220 | 165.5 | 208.1 |
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 M16×1.25 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (16 mm) and pitch (1.25 mm):
- Fundamental triangle height: H = (√3/2) × P = 1.0825 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 15.1881 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 14.4664 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 14.6469 mm
- Thread depth: 5H/8 = 0.6766 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 170.57 mm²