M18×1.0 Thread Specifications
Complete dimensions for M18×1.0 fine pitch thread per ISO 724. Pitch: 1.0mm (25.4 TPI equivalent).
Thread Dimensions
| Designation | M18×1.0 |
| Thread Series | ISO Metric Fine |
| Pitch | 1.0 mm (25.4 TPI) |
| Major Diameter (d) | 18 mm (0.7087") |
| Pitch Diameter (d₂) | 17.3505 mm (0.6831") |
| Minor Diameter — External (d₁) | 16.7731 mm (0.6604") |
| Minor Diameter — Internal (D₁) | 16.9175 mm (0.666") |
| Thread Depth | 0.5413 mm |
| Tensile Stress Area | 228.63 mm² |
| Fundamental Triangle Height (H) | 0.866 mm |
Tap Drill Size
Recommended tap drill: 17.0 mm
Calculated minor diameter (D₁): 16.92 mm. Closest standard metric drill: 17.0 mm.
Closest inch drill: 43/64" (0.6719" / 17.07 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 51.4 | 91.5 |
| 4.8 | 310 | 420 | 70.9 | 96.0 |
| 5.8 | 380 | 520 | 86.9 | 118.9 |
| 8.8 | 580 | 800 | 132.6 | 182.9 |
| 9.8 | 650 | 900 | 148.6 | 205.8 |
| 10.9 | 830 | 1040 | 189.8 | 237.8 |
| 12.9 | 970 | 1220 | 221.8 | 278.9 |
Proof load = stress area × proof stress. Per ISO 898-1.
Related Thread Sizes
Common Applications
- Structural connections
- Heavy equipment
- Pressure vessels
- Large flanges
How M18×1.0 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (18 mm) and pitch (1.0 mm):
- Fundamental triangle height: H = (√3/2) × P = 0.866 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 17.3505 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 16.7731 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 16.9175 mm
- Thread depth: 5H/8 = 0.5413 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 228.63 mm²