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TAP DRILL SIZES FOR THREAD FORMING TAPS

 

TAP SIZE TAP DRILL SIZE DECIMAL EQUIV.  PERCENT OF THREAD
0-80 1.35mm
#54
.0531
.0550
81
59
1-64 1.65mm
#51
.0650
.0670
75
56
1-72 1.65mm
#51
.0650
.067
85
64
2-56 1.95mm
#47
2.0mm
.0768
.0785
.0787
76
62
60
2-64 #47
2.0mm
2.05mm
.0785
.0787
.080
71
69
49
3-48 2.25mm
#43
2.3mm
.0886
.0890
.0906
73
71
59
3-56 #43
2.3mm
2.35mm
.0890
.0906
.0925
82
69
54
4-40 #39
#38
2.6mm
.0995
.1015
.1024
74
62
57
4-48 #38
2.6mm
#37
.1015
.1024
.1040
74
68
57
5-40 #34
2.9mm
#32
.1110
.1142
.1160
82
64
53
5-44 #33
2.9mm
#32
.1130
.1142
.1160
78
70
58
6-32 3.1mm
1/8
3.2mm
.1220
.1250
.126
75
61
56
6-40 1/8
3.2mm
#30
.125
.126
.1285
76
71
56
8-32 3.75mm
#25
#24
.1476
.1485
.1520
77
68
56
8-36 #25
#24
#23
.1495
.1520
.1540
77
64
53
10-24 #18
11/64
#17
.1695
.1719
.1730
72
64
60
10-32 #17
#16
#15
.1730
.177
.1800
80
61
47
12-24 #10
5.0mm
#7
.1935
.1968
.2011
79
68
53
12-28 5.0mm
5.1mm
13/64
.1968
.2008
.2031
79
63
53
1/4-20 5.7mm
#1
5.9mm
.2244
.2280
.2323
75
65
52
1/4-28 5.9mm
15/64
6.0mm
.2323
.2344
.2362
73
64
57
5/16-18 7.25mm
I
7.4mm
.2854
.2900
.2913
72
60
56
5/16-24 7.4mm
M
19/64
.2913
.2950
.2969
75
62
55
3/8-16 8.75mm
S
8.9mm
.3445
.3480
.3504
72
64
58
3/8-24 9.0mm
23/64
.3543
.3594
73
55
7/16-14 Y
13/32
Z
.4040
.4062
.4130
69
64
50
7/16-20 Z .4130 72
1/2-13 15/32
12mm
.4688
.4724
60
53
1/2-20 12mm .4724 81

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Last modified: November 29, 2001