Drill and Tap Sizes

A photo of some of my screw and bolt taps and three tap handles
A photo of some of my screw and bolt taps and three tap handles

This drill and tap chart was copied from my old html site.   It does not work well with WordPress.  I need to come up with a new idea for displaying the dimensions and their tap sizes.  This page is best viewed horizontally.

Drill Bit Sizes For Tapping New Threads


1/64
17/64
33/64
49/64
.1mm
8mm
17mm

3/64
19/64
35/64
51/64
1mm
9mm
18mm

5/64
21/64
37/64
53/64
2mm
10mm
19mm

7/64
23/64
39/64
55/64
3mm
11mm
20mm

9/64
25/64
41/64
57/64
4mm
12mm
21mm

11/64
27/64
43/64
59/64
5mm
13mm
22mm

13/64
29/64
45/64
61/64
6mm
14mm
23mm

15/64
31/64
47/64
63/64
7mm
15mm
24mm

16mm
25mm

Minimum and maximum drill sizes are indicated for many taps.  A smaller hole will have tighter threads, but will be more work to tap in hard materials.  A smaller hole (Where 75% of the thread surfaces will make contact) is a good idea in soft metals such as copper or brass.  Not responsible for errors and omissions regarding the content of this page.

Fraction
(Inches)		 Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch

Coarse
Pitch
.003937
.1mm
.0059055 .15
.007874 .2
.0098425 .25
.011811 .3
.0135 80
.0145 79
1/64 .015625 .39688
.015748 .4
.0160 78
.0177165 .45
.0180 77
.019685 .5
.0200 76
.0210 75
.0216535 .55
.0225 74
.023622 .6
.0240 73
.0250 72
.0255905 .65
.0260 71
.0280 70
.027559 .7
.0292 69
.0295275 .75
.0310 68
1/32 .031250 .79375
.031496 .8
.0320 67
.0330 66
.0334645 .85
.0350 65
.035433 .9
.0360 64
.0370 63
.0374015 .95
.0380 62
.0390 61

 

Photo of a thread restoring file used for restoring threads on screws and bolts.
Thread restoring file  used for restoring threads on screws and bolts.

 

Fraction
(Inches)		 Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size

of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch

Coarse
Pitch
.03937
1mm		 .2 .25
.04 60
.041 59
.0413385 1.05
.042 58
.043 57
.043307 1.1 .25
.0452755 1.15
.0465 56 0-80
3/64 .046875 1.19063
0-80


75%		 .318
.047244 1.2mm .2 .25
.048 0-80
.0492125 1.25
.051181 1.3
.052 55 8-80
50%
.0531495 1.35
.055 54
.055118 1.4mm .2 .3
.057 1-64
.0570865 1.45
.059 1-72
.059055 1.5mm .3
.0595 53
1-64,1-72


75%
.0610235 1.55
1/16 .062500 1.58750 1-64
50%
.062992 1.6mm .2 .35
.0635 52 0
.0635 52 1-72
50%
.0649605 1.65
.066929 1.7mm .2, .25 .35
.0670 51 2-56
.068 2-56
.0688975 1.75
.0700 50 2-64
.070866 1.8mm .2 .35
.0728345 1.85
.0730 49
.074803 1.9
.0760 48 1
.0767715 1.95
.078 3-48
5/64 .078125 1.98438 3-48
.0785 47 3-48

 

 

Fraction
(Inches)		 Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)

Tap
Drill
Size		 Fine
Pitch

Coarse
Pitch
Threads
per
Inch
(TPI)
.07874 M2 .25, .35 .4
.0807085 2.05
.0810 46 3-56
.0820 45 3-56
.082677 2.1
.0846455 2.15
.0860 44 4-40
.086614 2.2mm .45
.087 4-40
.0885825 2.25
.0890 43 4-40
.090551 2.3mm .25, .35 .4
.091 4-48
.0925195 2.35
.0935 42 4-48
3/32 .093750 2.38125 4-48
.094488 2.4
.0960 41
.0964565 2.45
.0980 40 5-40
.098425 2.5mm .35 .45
.0995 39 5-40
.100 5-40
.1015 38 5-44
.102 5-44
.102362 2.6mm .25, .35 .45
.1040 37
.106299 2.7
.1065 36 6-32
.107
.1082675 2.75
7/64 .109375 2.77813 6-32
.1100 35 6-32
.110236 2.8
.1110 34 6-32
.1130 33 6-32,
6-40
.114173 2.9
.1160 32 6-32,
6-40
.11811 M3
41, 2.6mm


75%		 .35 73
TPI
.11811 M3
2.5mm


75%		 .5 51
TPI
.1200 31 6-40
.122047 3.1
1/8 .125000 3.17500
.125984 3.2
.1279525 3.25
.1285 3.26390 30
.129921 3.3
.133
.133858 3.4
.1360 3.45440 29 8-32,
8-36


75%
.137795 3.5mm .35 .6
.1405 3.56870 28 8-32,
8-36
9/64 .140625 3.571875
.141732 3.6
.1440 27 8-32
50%
.145669 3.7
.1470 26 8-36
50%
.1476375 3.75
.148
.1495 25 10-24
.149606 3.8
.1520 24 10-24
.153543 3.9
.1540 23 10-24
5/32 .156250 3.96875 10-24
.1570 22 10-24

 

 

Fraction
(Inches)		 Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch
Coarse
Pitch
.15748 M4 .5 .7
.1590 21 10-24,
10-32
.1610 20 10-24,
10-32
.161417 4.1
.165354 4.2
.1660 19 10-32
.1673225 4.25
.169291 4.3
.1695 18 10-32
11/64 .171875 4.36563
.1730 17
.173228 4.4
.174
.1770 16 12-24
.177165 4.5mm .75
.1800 15 12-24
.181102 4.6
.1820 14 12-28
.1850 4.7 13 12-28,
12-32
.1870075 4.75
3/16 .187500 4.76250
.188976 4.8 12 12-24,
12-28
.1910 11 12-28
.192913 4.9
.1935 10
.1960 9
.196850
M5		 .5 .8
.1990 8
.200
.200787 5.1
13/64 .203125 5.15938 1/4-20
.204724 5.2
.2055 5 1/4-20
.2066925 5.25
.208661 5.3
.2090 4 1/4-20
.212598 5.4
.2130 3 1/4-28
.214 1/4-28
.216535 5.5
7/32 .218750 5.55625 1/4-20,
-28, -32
.220472 5.6
.2210 2
.224409 5.7
.2263775 5.75
.2280 1 1/4-28,
1/4-32
.228346 5.8
.232283 5.9
.2340 A
15/64 .234375 5.95313

 

1/64
3/64
5/64		 7/64 9/64 11/64 13/64 15/64 17/64 19/64 21/64 23/64 25/64 27/64 29/64 31/64
33/64 35/64 37/64 39/64 41/64 43/64 45/64 47/64 49/64 51/64 53/64 55/64 57/64 59/64 61/64 63/64

 


Fraction
(Inches)
Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch
Coarse
Pitch
.23622 M6 .75 1
.238 B
.240157 6.1
.242 C
.244094 6.2
.246 6.25 D
.248031 6.3
1/4 .25 6.35000 E
.251968 6.4
.255905 6.5
.257 F 5/16-18
.259842 6.6
.261 G 5/16-18
.263779 6.7
17/64 .265625 6.74688
.2657475 6.75
.266 H 5/16-24
.267716 6.8
.271 5/16-24
.271653 6.9
.272 I 5/16-24
.27559 7mm 1
.277 J
.279527 7.1
.2811 K
9/32 .28125 7.14375
.283464 7.2
.2854325 7.25
.287401 7.3
.29 L
.291338 7.4
.295 M
.295275 7.5
19/64 .296875 7.54063
.299212 7.6
.302 N
.303149 7.7
.3051175 7.75
.307086 7.8
.311023 7.9
.312 3/8-16
5/16 .3125 7.9375 3/8-16

 

 


Fraction
(Inches)
Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch
Coarse
Pitch
.31496 M8 1 1.25
.316 O 3/8-16
.318897 8.1
.322834 8.2
.323 P
.3248025 8.25
.326771 8.3
21/64 .328125 8.33438 3/8-24
.330708 8.4
.332 Q 3/8-24
.333 3/8-24
.334645 8.5
.338582 8.6
.339 R
.342519 8.7
11/32 .34375 8.73125
.3444875 8.75
.346456 8.8
.348 S
.350393 8.9
.35433 9mm 1.25
.358 T
.358267 9.1
23/64 .359375 9.12813 7/16-14
.362204 9.2
.3641725 9.25
.366 7/16-14
.366141 9.3
.368 U 7/16-14
.370078 9.4
.374015 9.5
3/8 .375 9.525
.377 V
.377952 9.6
.381889 9.7
.385826 9.8
.386 W 7/16-20
.388 7/16-20
.389763 9.9
25/64 .390625 9.92188 7/16-20

 

 

Fraction
(Inches)		 Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch
Coarse
Pitch
.3937 M10 1.25 1.5
.397 X
.404 Y
13/32 .40625 10.31875
.413 Z
.413385 10.5
27/64 .421875 10.71563 1/2-13
.423 1/2-13
.43307 11mm 1 1.5
7/16 .4375 11.1125
.45 1/2-20
.452755 11.5
29/64 .453125 11.50938 1/2-20
15/32 .46875 11.90625
.47244 M12 1.25,
1.5		 1.75
.479 9/16-12
31/64 .484375 12.30313 9/16-12
.492125 12.5
1/2″ .5″ 12.7 9/16-18
.507 9/16-18
.51181 13mm
33/64 .515625 13.09688
17/32 .53125 13.49375 5/8-11
.531495 13.5
.534 5/8-11
35/64 .546875 13.89063

 

 


Fraction
(Inches)
Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch
Coarse
Pitch
.55118
M14		 1.5
2

9/16		 .5625 14.28750 5/8-18
.569 5/8-18
.570865 14.5

37/64		 .578125 14.68438
.59055
15mm

19/32		 .59375 15.08125

39/64		 .609375 15.47813
.610235 15.5

5/8		 .625 15.875
.62992
M16		 1.5

41/64		 .640625 16.27188
.649605 16.5
.65 3/4-10

21/32		 .65625 16.66875 3/4-10
.66929
17mm

43/64		 .671875 17.06563

11/16		 .6875 17.4625 3/4-16
.688 3/4-16
.688975 17.5

45/64		 .703125 17.85938
.70866
M18		 1.5

23/32		 .71875 18.25625
.728345 18.5

47/64		 .734375 18.65313
.74803
19mm

3/4		 .75 19.05
.764 7/8-9

49/64		 .765625 19.44668 7/8-9
.767715 19.5

25/32		 .78125 19.84375

 

 

Fraction
(Inches)		 Decimal

(Inches)		 Milli-
meters		 Drill
Number
or Letter		 Tap

(Size
of
Screw &
Threads
per Inch)
Tap
Drill
Size		 Fine
Pitch
Coarse
Pitch
.7874
M20		 1.5
51/64 .796875 20.24063 7/8-14
.804 7/8-14
13/16 .8125 20.6375
.82677 21mm
53/64 .828125 21.03438
27/32 .84375 21.43125
.846455 21.5
55/64 .859375 21.83813
.86614
22mm
7/8 .875 22.225 1″-8
.885825 22.5
57/64 .890625 22.62187 1″-8
.905510
23mm
29/32 .90625 23.01875
59/64 .921875 23.41563 1″-12,
1″-14
.925195 23.5
.929 1″-14
15/16 .9375 23.81250 1″-14
.94488
M24		 1.5

61/64		 24.209
.964565 24.5
.982
25mm		 1
1/8″-7
63/64 .984375 25.00312 1
1/8″-7
1″ 1.000″ 25.40000 1
1/8″-7

 

 

 

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