Taper pipe tap standards

Dimensional standards for taper pipe taps—threads per inch, square size, overall length and tap drill by pipe size.

Taper pipe tap standards
Pipe tap sizeThreads per inchSize of squareOverall lengthTap drill A.S.A.
1/16 [.062]27.2342.125D (.246)
1/8 [.125]27.2342.125R (.339)
1/8 [.125]27.3282.125R (.339)
1/4 [.250]18.4212.4377/16
3/8 [.375]18.5312.56237/64
1/2 [.500]14.5153.12545/64
3/4 [.750]14.6793.25059/64
1. [1.000]11.5.8433.7501-5/32
1-1/4 [1.250]11.5.9844.0001-1/2
1-1/2 [1.500]11.51.1254.2501-47/64
2. [2.000]11.51.4064.5002-41/64