7/8-14 UNF Thread Specifications
Complete dimensions for 7/8-14 UNF (Unified National Fine) thread per ASME B1.1. TPI: 14, Pitch: 0.07143" (1.814 mm).
Thread Dimensions
| Designation | 7/8-14 UNF |
| Threads Per Inch (TPI) | 14 |
| Pitch | 0.07143" (1.814 mm) |
| Major Diameter | 0.875" (22.225 mm) |
| Pitch Diameter | 0.8286" (21.047 mm) |
| Minor Diameter (External) | 0.7874" (19.999 mm) |
| Minor Diameter (Internal) | 0.7977" (20.261 mm) |
| Thread Depth | 0.03866" (0.982 mm) |
| Tensile Stress Area | 0.50947 in² (328.7 mm²) |
Tap Drill Size
Recommended tap drill: 51/64" (0.7969" / 20.24 mm)
Calculated minor diameter (internal): 0.7977" (20.26 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 | 28,021 | 37,701 |
| Grade 5 | 85,000 | 120,000 | 43,305 | 61,136 |
| Grade 8 | 120,000 | 150,000 | 61,136 | 76,420 |
Same Size, Different Series
Common Applications
- Heavy structural, industrial equipment, anchor bolts
- Fine thread applications