Thread and Tap Drill Sizes

image of tap drill bits socket head cap screw

How to use these charts:

Drill sizes come in three US/English groups and one metric group. The three US/English groups are fractional sizes (such as 1/8" 1/4" etc), letter sizes (such as A, B, etc), and Number sizes such as 1 - 80.

Look down the left most column to find the screw size that you will be tapping a hole for or drilling a clearance hole for. Read across in the same row to find the drill size for the material you will be drilling in. If you need a clearance hole, then read across further to find the drill size for either a close fitting hole or a loose fitting hole.

US English Chart

Metric Chart

Pipe Thread Chart

 

US English Tap Drill Chart
Machine Screw Size
Number of Threads Per Inch
Minor Dia.
Tap Drills
Clearance Hole Drills

Aluminum, Brass & Plastics

75% Thread

Stainless Steel, Steels & Iron

50% Thread
All Materials
Close Fit
Free Fit
No. or Dia.
Major Dia.
Drill Size
Decimal Equiv.
Drill Size
Decimal Equiv.
Drill Size
Decimal Equiv.
Drill Size
Decimal Equiv.
0 .0600 80 .0447 3/64 .0469 55 .0520 52 .0635 50 .0700
1 .0730 64 .0538 53 .0595 1/16 .0625 48 .0760 46 .0810
72 .0560 53 .0595 52 .0635
2 .0860 56 .0641 50 .0700 49 .0730 43 .0890 41 .0960
64 .0668 50 .0700 48 .0760
3 .0990 48 .0734 47 .0785 44 .0860 37 .1040 35 .1100
56 .0771 45 .0820 43 .0890
4 .1120 40 .0813 43 .0890 41 .0960 32 .1160 30 .1285
48 .0864 42 .0935 40 .0980
5 .1250 40 .0943 38 .1015 7/64 .1094 30 .1285 29 .1360
44 .0971 37 .1040 35 .1100
6 .1380 32 .0997 36 .1065 32 .1160 27 .1440 25 .1495
40 .1073 33 .1130 31 .1200
8 .1640 32 .1257 29 .1360 27 .1440 18 .1695 16 .1770
36 .1299 29 .1360 26 .1470
10 .1900 24 .1389 25 .1495 20 .1610 9 .1960 7 .2010
32 .1517 21 .1590 18 .1695
12 .2160 24 .1649 16 .1770 12 .1890 2 .2210 1 .2280
28 .1722 14 .1820 10 .1935
32 .1777 13 .1850 9 .1960
1/4 .2500 20 .1887 7 .2010 7/32 .2188 F .2570 H .2660
28 .2062 3 .2130 1 .2280
32 .2117 7/32 .2188 1 .2280
5/16 .3125 18 .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 .3750 16 .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

.4375

 14 .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 .5000 13 .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 .5625 12 .4603 31/64 .4844 33/64 .5156 37/64 .5781 19/32 .5938
18 .4943 33/64 .5156 17/32 .5312
24 .5114 33/64 .5156 17/32 .5312
5/8 .6250 11 .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 .6875 24 .6364 41/64 .6406 21/32 .6562 45/64 .7031 23/32 .6562

3/4

.7500

 10 .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 .8125 20 .7512 49/64 .7656 25/32 .7812 53/64 .8281 27/32 .8438
7/8 .8750 9 .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 .9375 20 .8762 57/64 .8906 29/32 .9062 61/64 .9531 31/32 .9688
1 1.000 8 .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 1.0625 18 .9943 1.000 1.000 1-1/64 1.0156 1-5/64 1.0781 1-3/32 1.0938
1-1/8 1.1250 7 .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 1.1875 18 1.1193 1-1/8 1.1250 1-9/64 1.1406 1-13/64 1.2031 1-7/32 1.2188

1-1/4

1.2500

 7 1.0747 1-7/64 1.1094 1-5/32 1.1562

1-17/64

1.2656

1-9/32

1.2812
12 1.1478 1-11/64 1.1719 1-13/64 1.2031
18 1.1818 1-3/16 1.1875 1-13/64 1.2031
1-5/16 1.3125 18 1.2443 1-1/4 1.2500 1-17/64 1.2656 1-21/64 1.3281 1-11/32 1.3438
1-3/8 1.3750 6 1.1705 1-7/32 1.2187 1-17/64 1.2656 1-25/64 1.3906 1-13/32 1.4062
12 1.2728 1-19/64 1.2969 1-21/64 1.3281
18 1.3068 1-5/16 1.3125 1-21/64 1.3281
1-7/16 1.4375 18 1.3693 1-3/8 1.3750 1-25/64 1.3906 1-29/64 1.4531 1-15/32 1.4688
1-1/2 1.500 6 1.2955 1-11/32 1.3437 1-25/64 1.3906 1-33/64 1.5156 1-17/32 1.5312
12 1.3978 1-27/64 1.4219 1-7/16 1.4375
18 1.4318 1-7/16 1.4375 1-29/64 1.4531
1-9/16 1.5625 18 1.4943 1-12 1.500 1-33/64 1.5156 1-37/64 1.5781 1-19/32 1.5938
1-5/8 1.625 18 1.5568 1-9/16 1.5625 1-37/64 1.5781 1-41/64 1.6406 1-21/32 1.6562
1-11/16 1.6875 18 1.6193 1-5/8 1.6250 1-41/64 1.6406 1-45/64 1.7031 1-23/32 1.7188
1-3/4 1.750 5 1.5046 1-9/16 1.5625 1-5/8 1.6250 1-49/64 1.7659 1-25/32 1.7812

 

Metric Tap Drill Chart
Tap size
Major
Dia (mm)
Threads
per
Tap Drill
(mm)
Tap Drill
(inch)
Clearance
(mm)
Clearance
(inch)
M1.6x0.35 1.6 0.35 1.25 #55 1.8 #49
M2x0.4 2.0 0.40 1.60 #52 2.4 #41
M2.5x0.45 2.5 0.45 2.05 #46 2.9 #32
M3x.05 3.0 0.50 2.50 #39 3.4 #29
M3.5x0.6 3.5 0.60 2.90 #32 3.9 #23
M4x0.7 4.0 0.70 3.30 #30 4.5 #16
M5x0.8 5.0 0.80 4.20 #19 5.5 7/32
M6x1 6.0 1.00 5.0 #8 6.6 G
M8x1.25 8.0 1.25 6.8 H 9.0 T
M8x1 8.0 1.00 7.0 J 9.0 T
M10x1.5 10.0 1.50 8.5 R 12.0 31/64
M10x1.25 10.0 1.25 8.8 11/32 12.0 31/64
M12x1.75 12.0 1.75 10.2 13/32 14.0 35/64
M12x1.25 12.0 1.25 10.8 27/64 14.0 35/64
M14x2 14.0 2.00 12.0 15/32 16.0 5/8
M14x1.5 14.0 1.5 12.5 1/2 16.0 5/8
M16x2 16.0 2.00 14.0 35/64 18.0 45/64
M16x1.5 16.0 1.50 14.5 37/64 18.0 45/64
M18x2.5 18.0 2.50 15.5 39/64 20.0 51/64
M18x1.5 18.0 1.50 16.5 21/32 20.0 51/64
M20x2.5 20.0 2.50 17.5 11/16 22.0 7/8
M20x1.5 20.0 1.50 18.5 47/64 22.0 7/8
M22x2.5 22.0 2.50 19.5 49/64 25.0 1
M22x1.5 22.0 1.50 20.5 13/16 25.0 1
M24x3 24.0 3.00 21.0 53/64 27.0 1-5/64
M24x2 24.0 2.00 22.0 7/8 27.0 1-5/64
M27x3 27.0 3.00 24.0 15/16 30.0 1-3/16
M27x2 27.0 2.0 25.0 1 30.0 1-3/16

 

Pipe Threads
-
American Standard
British Standard
Nominal
OD
Threads
per inch
NPT
NPS
Threads
per inch
Drill size
1/16 27 D 1/4 28 G
1/8 27 R S 28 11/32
1/4 18 7/16 29/64 19 15/32
3/8 18 37/64 19/32 19 39/64
1/2 14 23/32 47/64 14 3/4
5/8 - - - 14 53/64
3/4 14 59/64 15/16 14 31/32
7/8 - - - 14 1-7/64
1 11.5 1-5/32 1-3/16 11 1-7/32

 

 
 
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