Pre Tap Drill Size

Pipe Tap NPSC

Tap
Drill Size
Decimal Equivalent
2in - 11-1/2
2in 13/64
2.2031
1in1/2 - 11-1/2
1in 47/64
1.7343
1in1/4 - 11-1/2
1in 1/2
1.500
1in - 11-1/2
1in 5/32
1.1562
3/4 - 14
59/64
0.9218
1/2 - 14
18MM
0.7086
3/8 - 18
37/64
0.5781
1/4 - 18
7/16
0.4375
1/8 - 27
Q .332
0.332
1/16 - 27
1/4
0.250