Unifed National Fine (UNF) tapping drill sizes.

Nominal Dia Pitch Pitch TPI Tapping drill Dia mm
No. 0 80 1.25
No. 1 72 1.55
No. 2 64 1.90
No. 3 56 2.15
No. 4 48 2.40
No. 5 44 2.70
No. 6 40 2.95
No. 8 36 3.50
No. 10 32 4.10
No. 12 28 4.70
1/4" 28 5.50
5/16" 24 6.90
3/8" 24 8.50
7/16" 20 9.90
1/2" 20 11.50
9/16" 18 12.90
5/8" 18 14.50
3/4" 16 17.50
7/8" 14 20.40
1" 12 23.25
1.1/8" 12 26.50
1.1/4" 12 29.50
1.3/8" 12 32.75
1.1/2" 12 36.00