|
NPT Size
|
Tap Drill Size (in.)
|
Decimal Equivalent (in.)
|
|
1/16 – 27
|
“C”
|
0.242
|
|
1/8 – 27
|
“Q”
|
0.332
|
|
1/4 – 18
|
7/16
|
0.438
|
|
3/8 – 18
|
9/16
|
0.562
|
|
1/2 – 14
|
45/64
|
0.703
|
|
3/4 – 14
|
29/32
|
0.906
|
|
1.0 – 11•1/2
|
1•9/64
|
1.141
|
|
1•1/4 – 11•1/2
|
1•31/64
|
1.484
|
|
1•1/2 – 11•1/2
|
1•23/32
|
1.719
|
|
2.0 – 11•1/2
|
2•3/16
|
2.188
|
|
2•1/2 – 8
|
2•39/64
|
2.609
|
|
3.0 – 8
|
3•15/64
|
3.234
|
Metric Tap Drill Sizes
Standard UNC Tap Drill Sizes
Standard UNF Tap Drill Sizes