1/4-32 UNEF Thread Specifications
Complete dimensions for 1/4-32 UNEF (Unified National Extra Fine) thread per ASME B1.1. TPI: 32, Pitch: 0.03125" (0.794 mm).
Thread Dimensions
| Designation | 1/4-32 UNEF |
| Threads Per Inch (TPI) | 32 |
| Pitch | 0.03125" (0.794 mm) |
| Major Diameter | 0.25" (6.35 mm) |
| Pitch Diameter | 0.2297" (5.834 mm) |
| Minor Diameter (External) | 0.2117" (5.376 mm) |
| Minor Diameter (Internal) | 0.2162" (5.491 mm) |
| Thread Depth | 0.01691" (0.43 mm) |
| Tensile Stress Area | 0.03786 in² (24.4 mm²) |
Tap Drill Size
Recommended tap drill: 7/32" (0.2188" / 5.56 mm)
Calculated minor diameter (internal): 0.2162" (5.49 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 | 2,082 | 2,802 |
| Grade 5 | 85,000 | 120,000 | 3,218 | 4,543 |
| Grade 8 | 120,000 | 150,000 | 4,543 | 5,679 |
Same Size, Different Series
Common Applications
- Precision assemblies
- Thin-wall tubing
- Aerospace fittings