Standard UN Tap Drill Sizes

Notice that the precentage of thread depth ranges from 56 to 82%.

 
 ******APPROVED UNC AND UNF, CLASS 2B, SCREW THREADS*******
	
 SERIES     THREAD         TAP DRILL      BODY DRILL  THD %
 -------- -----------    -------------- ------------- ------
   UNF    #0(.060)x80     1.25mm(.0492)  1/16(.0625)   58
   UNC    #1(.073)x64      #53(.0595)     #49(.073)    59
   UNF    #1(.073)x72     1.55mm(.061)    #49(.073)    58
 * UNC    #2(.086)x56      #50(.070)      #44(.086)    62
   UNF    #2(.086)x64      #49(.073)      #44(.086)    56
   UNC    #3(.099)x48      #45(.082)      #39(.0995)   56
   UNF    #3(.099)x56     2.1mm(.0827)    #39(.0995)   62
 * UNC    #4(.112)x40      #43(.089)      #33(.113)    65
   UNF    #4(.112)x48      3/32(.0938)    #33(.113)    60
   UNC    #5(.125)x40      #37(.104)      1/8(.125)    58
   UNF    #5(.125)x44      #37(.104)      1/8(.125)    63
 * UNC    #6(.138)x32      7/64(.1094)    9/64(.1406)  64
   UNF    #6(.138)x40      #32(.116)      9/64(.1406)  60
 * UNC    #8(.164)x32     3.5mm(.1378)    #19(.166)    57
   UNF    #8(.164)x36      #28(.1405)     #19(.166)    57
   UNC    #10(.190)x24     #23(.154)      #11(.191)    61
 * UNF    #10(.190)x32     #20(.161)      #11(.191)    64
   UNC    #12(.216)x24     #15(.180)      7/32(.2188)  61
   UNF    #12(.216)x28     #13(.185)      7/32(.2188)  60
 * UNC    1/4(.250)x20     #5(.2055)      1/4(.250)    64
   UNF    1/4(.250)x28     7/32(.2188)    1/4(.250)    60
 * UNC    5/16(.3125)x18   17/64(.2656)   5/16(.3125)  60
   UNF    5/16(.3125)x24     J(.277)      5/16(.3125)  60
 * UNC    3/8(.375)x16       P(.323)       3/8(.375)   60
   UNF    3/8(.375)x24       R(.339)       3/8(.375)   60
 * UNC    1/2(.500)x13     7/16(.4375)     1/2(.500)   60
   UNF    1/2(.500)x20    29/64(.4531)     1/2(.500)   67
   UNC    7/16(.438)x14   9.25mm(.3642)   7/16(.438)   82
   UNC    9/16(.562)x12   12.1mm(.4764)   9/16(.562)   82
   UNC    5/8(.625)x11    13.5mm(.5315)    5/8(.625)   82

		     * PREFERRED USAGE