AN Thread Sizes                NPT Thread Sizes

AN Size         Thread                                                                Pipe Size         Threads / Inch
  - 2             5/16 - 24                                                                1/16                         27
 - 3              3/8 - 24                                                                  1/8                           27 
  - 4             7/16 - 20                                                                1/4                           18                
 - 5              1/2 - 20                                                                  3/8                           18
  - 6             9/16 - 18                                                                1/2                           14
- 8              3/4 - 16                                                                   3/4                           14
- 10             7/8 - 14                                                                    1                           11 1/2
- 12             1 1/16 - 12                                                             1 1/4                       11 1/2
- 16             1 5/16 - 12                                                             1 1/2                       11 1/2
- 20             1 5/8 - 12                                                                  2                          11 1/2
- 24            1 7/8 - 12
- 28             2 1/4 - 12
- 32             2 1/2 - 12