M20×1.0 Thread Specifications
Complete dimensions for M20×1.0 fine pitch thread per ISO 724. Pitch: 1.0mm (25.4 TPI equivalent).
Thread Dimensions
| Designation | M20×1.0 |
| Thread Series | ISO Metric Fine |
| Pitch | 1.0 mm (25.4 TPI) |
| Major Diameter (d) | 20 mm (0.7874") |
| Pitch Diameter (d₂) | 19.3505 mm (0.7618") |
| Minor Diameter — External (d₁) | 18.7731 mm (0.7391") |
| Minor Diameter — Internal (D₁) | 18.9175 mm (0.7448") |
| Thread Depth | 0.5413 mm |
| Tensile Stress Area | 283.22 mm² |
| Fundamental Triangle Height (H) | 0.866 mm |
Tap Drill Size
Recommended tap drill: 19.0 mm
Calculated minor diameter (D₁): 18.92 mm. Closest standard metric drill: 19.0 mm.
Closest inch drill: 3/4" (0.75" / 19.05 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 63.7 | 113.3 |
| 4.8 | 310 | 420 | 87.8 | 119.0 |
| 5.8 | 380 | 520 | 107.6 | 147.3 |
| 8.8 | 580 | 800 | 164.3 | 226.6 |
| 9.8 | 650 | 900 | 184.1 | 254.9 |
| 10.9 | 830 | 1040 | 235.1 | 294.5 |
| 12.9 | 970 | 1220 | 274.7 | 345.5 |
Proof load = stress area × proof stress. Per ISO 898-1.
Related Thread Sizes
Common Applications
- Structural connections
- Heavy equipment
- Pressure vessels
- Large flanges
How M20×1.0 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (20 mm) and pitch (1.0 mm):
- Fundamental triangle height: H = (√3/2) × P = 0.866 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 19.3505 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 18.7731 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 18.9175 mm
- Thread depth: 5H/8 = 0.5413 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 283.22 mm²