NPT Size
1/4" NPT
A workhorse port size for pneumatics, hydraulics, and general plumbing fittings.
Last verified: 2026-07-10
| TPIThreads per inch (NPT is tapered at 3/4" per foot). | 18 |
|---|---|
| Pipe OD(in)Actual outside diameter of the thread / pipe. | 0.54 |
| Tap drillTypical tap drill for cutting the internal NPT thread. | 7/16" (0.4375") |
| Typical use | Pneumatic/hydraulic ports, sensors, general fittings |
Other npt pipe thread chart
Sources
- ANSI/ASME B1.20.1 — pipe threads, general purpose (NPT): TPI and pipe OD
- Typical NPT tap-drill charts (machining practice)