What Size Drill Bit

2 NPT tap drill size

2-7/32"

Inches
2.2188
Millimetres
56.36
Threads per inch
11.5

Drill a 2-7/32" hole, then cut the 2 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.

2 NPT thread and hole sizes

Thread2 NPT National Pipe Taper, 11.5 threads per inch
Tap drill, no reamer2-7/32" 2.2188 in, 56.36 mm
Pitch0.0870 in 2.209 mm

Tools for this job

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