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.