US Tap and Drill Bit Size Table

Tap Fractional Drill Bit Number Drill Bit Letter Drill Bit
0-80 3/64 - -
1-64 - 53 -
2-56 - 50 -
3-48 - 47 -
4-40 3/32 43 -
5-40 - 38 -
6-32 7/64 35 -
8-32 - 29 -
10-24 5/32 25 -
10-32 5/32 21 -
12-24 11/64 16 -
1/4-20 13/64 7 -
1/4-28 7/32 3 -
5/16-18 17/64 - F
5/16-24 - - I
3/8-16 5/16 - -
3/8-24 21/64 - Q
7/16-14 23/64 - U
7/16-20 25/64 - -
1/2-13 27/64 - -
1/2-20 29/64 - -
9/16-12 31/64 - -
9/16-18 33/64 - -
5/8-11 17/32 - -
5/8-18 37/64 - -
3/4-10 21/32 - -
3/4-16 11/16 - -
Drill sizes are for 75% depth of thread.