US Tap and Drill Bit Size

Tap --Fractional Drill--Number Drill--Letter Drill


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 ---------------------------------