RECOMMENDATION TABLES: DRILL DIAMETERS FOR CUTTING TAPS
Drill diameter can be calculated from:
D = Dnom- P
ISO Metric Coarse Thread
TAP
M
1.6x0.35
1.8x0.35
2x0.4
2.2x0.45
2.5x0.45
3x0.5
3.5x0.6
4x0.7
4.5x0.75
5x0.8
6x1
7x1
8x1.25
9x1.25
10x1.5
11x1.5
12x1.75
14x2
16x2
18x2.5
20x2.5
22x2.5
24x3
27x3
30x3.5
33x3.5
36x4
39x4
42x4.2
45x4.5
48x5
52x5
Max.
Internal
Diam.
mm
1.321
1.521
1.679
1.833
2.138
2.599
3.010
3.422
3.878
4.334
5.153
6.153
6.912
7.912
8.676
9.676
10.441
12.210
14.210
15.744
17.744
19.744
21.252
24.252
26.771
29.771
32.270
35.270
37.799
40.799
43.297
47.297
DRILL
Diam.
mm
1.25
1.45
1.6
1.75
2.05
2.5
2.9
3.3
3.8
4.2
5
6
6.8
7.8
8.5
9.5
10.3
12
14
15.5
17.5
19.5
21
24
26.5
29.5
32
35
37.5
40.5
43
47
DRILL
Diam.
inch
3/64
54
1/16
50
46
40
33
30
27
19
9
15/64
H
5/16
Q
3/8
Y
15/32
35/64
39/64
11/16
49/64
53/64
61/64
1.3/64
1.5/32
1.1/4
1.3/8
D = Drill diameter (mm)
Dnom = Tap nominal diameter (mm)
P = Tap pitch (mm)
ISO Metric FINe Thread
TAP
MF
3x0.35
3.5x0.35
4x0.5
5x0.5
5.5x0.50
6x0.75
7x0.75
8x0.75
8x1
9x1
10x0.75
10x1
10x1.25
11x1
12x1
12x1.25
12x1.5
14x1
14x1.25
14x1.5
15x1
15x1.5
16x1
16x1.5
18X1
18X1.5
18X2
20X1
20X1.5
20X2
22X1
22X1.5
22X2
24X1
24X1.5
24X2
25X1
25X1.5
25x2
26x1.5
27x1.5
27x2
28x1.5
28x2
30x1.5
30x2
32x1.5
32x2
33x2
35x1.5
36x1.5
36x2
36x3
38x1.5
39x3
40x1.5
40x2
40x3
42x1.5
42x2
42x3
45x1.5
45X2
45X3
48X1.5
48X2
48X3
50X1.5
50X2
50X3
Max.
Internal
Diam.
mm
2.721
3.221
3.599
4.599
5.099
5.378
6.378
7.378
7.153
8.153
9.378
9.153
8.912
10.153
11.153
10.912
10.676
13.153
12.912
12.676
14.153
13.676
15.153
14.676
17.153
16.676
16.210
19.153
18.676
18.210
21.153
20.676
20.210
23.153
22.676
22.210
24.153
23.676
23.210
24.676
25.676
25.210
26.676
26.210
28.676
28.210
30.676
30.210
31.210
33.676
34.676
34.210
33.252
36.676
36.252
38.676
38.210
37.252
40.676
40.210
39.252
43.676
43.210
45.252
46.676
46.210
45.252
48.686
48.210
47.252
DRILL
DRILL
Diam.
mm
2.65
3.2
3.5
4.5
5
5.3
6.3
7.3
7
8
9.3
9
8.8
10
11
10.8
10.5
13
12.8
12.5
14
13.5
15
14.5
17
16.5
16
19
18.5
18
21
20.5
20
23
22.5
22
24
23.5
23
24.5
25.5
25
26.5
26
28.5
28
30.5
30
31
33.5
34.5
34
33
36.5
36
38.5
38
37
40.5
40
39
43.5
43
42
46.5
46
45
48.2
48
47
Diam.
inch
37
1/8
29
16
9
5
D
9/32
J
O
U
T
11/32
X
7/16
27/64
Z
17/32
1/2
31/64
35/64
17/32
19/32
9/16
43/64
41/64
5/8
3/4
47/64
45/64
53/64
13/16
25/32
29/32
7/8
55/64
ISO UNIFIED Coarse Thread
TAP
UNC
nr 2-56
nr 3-48
nr 4-40
nr 5-40
nr 6-32
nr 8-32
nr 10-24
nr 12-24
1/4-20
5/16-18
3/8-16
7/16-14
1/2-13
9/16-12
5/8-11
3/4-10
7/8-9
1-8
1.1/8-7
1.1/4-7
1.3/8-6
1.1/2-6
1.3/4-5
2-41/2
Max.
Internal
Diam.
mm
1.872
2.146
2.385
2.697
2.896
3.513
3.962
4.597
5.268
6.734
8.164
9.550
11.013
12.456
13.868
16.833
19.748
22.598
25.349
28.524
31.120
34.295
39.814
45.595
BSW Thread
DRILL
DRILL
TAP
Diam.
mm
1.85
2.1
2.35
2.65
2.85
3.5
3.9
4.5
5.1
6.6
8
9.4
10.8
12.2
13.5
16.5
19.5
22.25
25
28
30.75
34
39.5
45
Diam.
Inch
50
47
43
38
36
29
25
16
7
F
5/16
U
27/64
31/64
17/32
21/32
49/64
7/8
63/64
1.7/64
1.7/32
1.11/32
1.9/16
1.25/32
BSW
3/32
1/8
5/32
3/16
7/32
1/4
5/16
3/8
7/16
1/2
9/16
5/8
3/4
7/8
1
1.1/8
1.1/4
1.3/8
1.1/2
1.5/8
1.3/4
1.7/8
2
Number
of
t.p.i.
48
40
32
24
24
20
18
16
14
12
12
11
10
9
8
7
7
6
6
5
5
4.1/2
4.1/2
Max.
Internal
Diam.
mm
1.910
2.590
3.211
3.744
4.538
5.224
6.661
8.052
9.379
10.610
12.176
13.598
16.538
19.411
22.185
24.879
28.054
30.555
33.730
35.921
39.098
41.648
44.823
DRILL
Diam.
mm
1.85
2.55
3.2
3.7
4.5
5.1
6.5
7.9
9.2
10.5
12
13.5
16.5
19.25
22
24.75
28
30.5
33.5
35.5
39
41.5
44.5
BSP(G) Thread
ISO UNIFIED fine Thread
TAP
UNF
nr 2-64
nr 3-56
nr 4-48
nr 5-44
nr 6-40
nr 8-36
nr 10-32
nr 12-28
1/4-28
5/16-24
3/8-24
7/16-20
1/2-20
9/16-18
5/8-18
3/4-16
7/8-14
1-12
1.1/8-12
1.1/4-12
1.3/8-12
1.1/2-12
Max.
Internal
Diam.
mm
1.913
2.197
2.459
2.741
3.023
3.607
4.166
4.724
5.580
7.038
8.626
10.030
11.618
13.084
14.671
17.689
20.663
23.569
26.744
29.919
33.094
36.269
DRILL
DRILL
Diam.
mm
1.9
2.15
2.4
2.7
2.95
3.5
4.1
4.7
5.5
6.9
8.5
9.9
11.5
12.9
14.5
17.5
20.4
23.25
26.5
29.5
32.75
36
Diam
Inch
50
45
42
37
33
29
21
14
3
I
Q
25/64
29/64
33/64
37/64
11/16
13/16
59/64
1.3/64
1.11/64
1.19/64
1.27/64
TAP
G
1/8
1/4
3/8
1/2
5/8
3/4
7/8
1
1.1/4
1.1/2
1.3/4
2
2.1/4
2.1/2
2.3/4
3
Number
of
t.p.i.
28
19
19
14
14
14
14
11
11
11
11
11
11
11
11
11
Max.
Internal
Diam.
mm
8.848
11.890
15.395
19.172
21.128
24.658
28.418
30.931
39.592
45.485
51.428
57.296
63.342
72.866
79.216
85.566
DRILL
Diam.
mm
8.8
11.8
15.25
19
21
24.5
28.25
30.75
39.5
45
51
57
63
72.5
79
85.5
BSPT Thread
TAP
Rc
1/8
1/4
3/8
1/2
5/8
3/4
7/8
1
1.1/8
1.1/4
1.3/8
1.1/2
1.3/4
2
2.1/4
2.1/2
2.3/4
3
Drill
Number
of
t.p.i.
28
19
19
14
14
14
14
11
11
11
11
11
11
11
11
11
11
11
Diam.
mm
8.4
11.2
14.75
18.25
20.25
23.75
27.5
30
34.5
38.5
41
44.5
50
56
62
71.5
78
84