US Tap and Drill Bit Size and Reference Chart

Machine Screw Size Number of Threads Per Inch Major Diameter Minor Diameter Tap drills Clearance Drill
75% Thread for
Aluminum, Brass,
& Plastics		 50% Thread for
Steel, Stainless,
& Iron		 Close Fit Free Fit
Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv.
0 80 .0600 .0447 3/64 .0469 55 .0520 52 .0635 50 .0700
1 64 .0730 .0538 53 .0595 1/16 .0625 48 .0760 46 .0810
72 .0560 53 .0595 52 .0635        
2 56 .0860 .0641 50 .0700 49 .0730 43 .0890 41 .0960
64 .0668 50 .0700 48 .0760        
3 48 .0900 .0734 47 .0785 44 .0860 37 .1040 35 .1100
56 .0771 45 .0820 43 .0890        
4 40 1120 .0813 43 .0890 41 .0960 32 .1160 30 .1285
48 .0864 42 .0935 40 .0980        
5 40 1250 .0943 38 .1015 7/64 .1094 30 .1285 29 .1360
44 .0971 37 .1040 35 .1100        
6 32 .1380 .0997 36 .1065 32 .1160 27 .1440 25 .1495
40 .1073 33 .1130 31 .1200        
8 32 .1640 .1257 29 .1360 27 .1440 18 .1695 16 .1770
36 .1299 29 .1360 26 .1470        
10 24 1900 .1389 25 .1495 20 .1610 9 .1960 7 .2010
32 .1517 21 .1590 18 .1695        
12 24 0.216 .1649 16 .1770 12 .1890 2 .2210 1 .2280
28 .1722 14 .1820 10 .1935
32 .1777 13 .1850 9 .1960
1/4 20 0.2500 .1887 7 .2010 7/32 .2188 F .2570 H .2260
28 .2062 3 .2130 1 .2280
32 .2117 7/32 .2188 1 .2280
5/16 18 0.313 .2443 F .2570 J .2770 P .3230 Q .3320
24 .2614 I .2720 9/32 .2812
32 .2742 9/32 .2812 L .2900
3/8 16 .3750 .2983 5/16 .3125 Q .3320 W .3860 X .3970
24 .3239 Q .3320 S 3480
32 .3367 11/32 .3438 T .3580
7/16 14 0.438 .3499 U .3680 25/64 .3906 29/64 .4531 15/32 .4687
20 .3762 25/64 .3906 13/32 .4062
28 .3937 Y .4040 Z .4130
1/2 13 0.500 .4056 27/64 .4219 29/64 .4531 33/64 .5156 17/32 .5312
20 .4387 29/64 .4531 15/32 .4688
28 .4562 15/32 .4688 15/32 .4688
9/16 12 .5625 .4603 31/64 .4844 33/64 .5156 37/64 .5781 19/32 .5938
18 .4943 33/64 .5156 17/32 .5312
24 .5514 33/64 .5156 17/32 .5312
5/8 11 0.625 .5135 17/32 .5312 9/16 .5625 41/64 .6406 21/32 .6562
18 .5568 37/64 .5781 19/32 .5938
24 .5739 37/64 .5781 19/32 .5938
11/16 24 .5875 .6364 41/64 .6406 21/32 .6562 45/64 .7031 23/32 .7188
3/4 10 0.75 .6273 21/32 .6562 11/16 .6875 49/64 .7656 25/32 .7812
16 .6733 11/16 .6875 45/64 .7031
20 .6887 45/64 .7031 23/32 .7188
13/16 20 .8125 .7512 49/64 .7656 25/32 .7812 53/64 .8281 27/32 .8438
7/8 9 0.875 .7387 49/64 .7656 51/64 .7969 57/64 .8906 29/32 .9062
14 .7874 13/16 .8125 53/64 .8281
20 .8137 53/64 .8281 27/32 .8438
15/16 20 .9375 .8762 57/64 .8906 29/32 .9062 61/64 .9531 31/32 .9688
1 8 1 .8466 7/8 .8750 59/64 .9219 1-1/64 1.0156 1-1/32 1.0313
12 .8978 15/16 .9375 61/64 .9531
20 .9387 61/64 .9531 31/32 .9688
1-1/16 18 1.0625 .9943 1.000 1.000 1-1/64 1.1056 1-5/64 1.0781 1-3/32 1.0938
1-1/8 7 1.125 .9497 63/64 .9844 1-1/32 1.0313 1-9/64 1.1406 1-5/32 1.1562
12 1.0228 1-3/64 1.0469 1-5/64 1.0781
18 1.0568 1-1/16 1.0625 1-5/64 1.0781
1-3/16 18 1.1875 1.1193 1-1/8 1.1250 1-9/64 1.1406 1-13/64 1.2031 1-7/32 1.2188