1-20 UNEF Thread Specifications
Complete dimensions for 1-20 UNEF (Unified National Extra Fine) thread per ASME B1.1. TPI: 20, Pitch: 0.05" (1.27 mm).
Thread Dimensions
| Designation | 1-20 UNEF |
| Threads Per Inch (TPI) | 20 |
| Pitch | 0.05" (1.27 mm) |
| Major Diameter | 1" (25.4 mm) |
| Pitch Diameter | 0.9675" (24.575 mm) |
| Minor Diameter (External) | 0.9387" (23.842 mm) |
| Minor Diameter (Internal) | 0.9459" (24.025 mm) |
| Thread Depth | 0.02706" (0.687 mm) |
| Tensile Stress Area | 0.71074 in² (458.5 mm²) |
Tap Drill Size
Recommended tap drill: 61/64" (0.9531" / 24.21 mm)
Calculated minor diameter (internal): 0.9459" (24.02 mm)
Proof Loads by SAE Grade
| Grade | Proof Stress (psi) | Tensile Strength (psi) | Proof Load (lbf) | Tensile Load (lbf) |
|---|---|---|---|---|
| Grade 2 | 55,000 | 74,000 | 39,091 | 52,595 |
| Grade 5 | 85,000 | 120,000 | 60,413 | 85,289 |
| Grade 8 | 120,000 | 150,000 | 85,289 | 106,611 |
Same Size, Different Series
Common Applications
- Precision assemblies
- Thin-wall tubing
- Aerospace fittings