1/4 NPT tap drill size
7/16"
- Inches
- 0.4375
- Millimetres
- 11.11
- Threads per inch
- 18
Drill a 7/16" hole, then cut the 1/4 NPT thread with a taper pipe tap. This is the size for drilling and tapping with no reamer step.
Charts differ on pipe threads. Some list a smaller drill because they assume the hole is taper-reamed first. If you ream, use the drill size your tap or reamer maker lists.
1/4 NPT thread and hole sizes
| Thread | 1/4 NPT National Pipe Taper, 18 threads per inch |
|---|---|
| Tap drill, no reamer | 7/16" 0.4375 in, 11.11 mm |
| Pitch | 0.0556 in 1.411 mm |
Tools for this job
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