1/2" NPT Thread Specifications
Complete dimensions for 1/2" NPT (National Pipe Taper) thread per ASME B1.20.1. TPI: 14, Pitch: 0.07143" (1.814 mm). Taper: 1 in 16 on diameter (3/4" per foot).
Thread Dimensions
| Designation | 1/2" NPT |
| Nominal Pipe Size | 1/2" |
| TPI | 14 |
| Pitch | 0.07143" (1.814 mm) |
| Outside Diameter | 0.8400" (21.34 mm) |
| Pitch Diameter at E0 (hand-tight) | 0.75843" (19.264 mm) |
| Pitch Diameter at E1 (wrench makeup) | 0.77843" (19.772 mm) |
| Minor Diameter at E0 | 0.72235" (18.348 mm) |
| Taper Angle | 1.7899° (1:16 taper ratio, 3/4"/ft) |
| Thread Depth (h = 0.8p) | 0.05714" (1.451 mm) |
Values per ASME B1.20.1 Table 1. E0 = hand-tight engagement pitch diameter; E1 = wrench-makeup pitch diameter.
Tap Drill Size
Tap drill: 23/32" (0.7188" / 18.26 mm)
NPT tap drills allow the tap to cut the taper thread. The tap itself creates the taper geometry; drill size provides initial clearance at the large end.
Common Applications
- Plumbing connections
- Gas piping
- Hydraulic fittings
- Pneumatic connections