NPT - National Pipe Thread Taper - ANSI B1.20.1 | |||||
Pipe Size (inches) | Threads/Inch | Approx. Length of Thread (inches) | Approx Number of Threads to be cut | Nominal Outside Pipe Diameter (inches) | Tap Drill |
1/8" | 27 | 3/8" | 10 | 0.405" | |
1/4" | 18 | 5/8" | 11 | 0.540" | 7/16" |
3/8" | 18 | 5/8" | 11 | 0.675" | 37/64" |
1/2" | 14 | 3/4" | 10 | 0.840" | 23/32" |
3/4" | 14 | 3/4" | 10 | 1.050" | 59/64" |
1" | 11-1/2 | 7/8" | 10 | 1.315" | 1-5/32" |
1-1/4" | 11-1/2 | 1" | 11 | 1.660" | 1-1/2" |
1-1/2" | 11-1/2 | 1" | 11 | 1.900" | 1-47/64" |
2" | 11-1/2 | 1" | 11 | 2.375" | 2-7/32" |
2-1/2" | 8 | 1-1/2" | 12 | 2.875" | 2-5/8" |