As a rule of thumb, for Metric threads, the tapping drill can be calculated by subtracting the pitch from the diameter of the thread. eg for an M5x0.75 thread the tapping drill is 5-0.75mm = 4.25mm.
For Imperial (inch) threads the tapping drill size is calculated in the same way, diameter minus pitch. eg for 3/4.10 UNC pitch = 0.1, diameter = 0.75, tapping drill = 0.65 = 16.5mm.
To calculate tapping drill size for metric threads subtract the pitch from the major diameter, Select the next larger standard drill size.
THREAD SIZE |
DRILL (MM) |
THREAD SIZE |
DRILL (MM) |
THREAD SIZE |
DRILL (MM) |
---|---|---|---|---|---|
M1x0.25 |
0.75 |
M9x0.75 |
8.3 |
M18x2 |
16 |
M1.2x0.25 |
0.95 |
M9x1 |
8 |
M18x2.5 |
15.5 |
M1.4x0.3 |
1.1 |
M9x1.25 |
7.8 |
M20x1 |
19 |
M1.6x0.35 |
1.25 |
M10x0.5 |
9.5 |
M20x1.5 |
18.5 |
M1.8x0.35 |
1.45 |
M10x0.75 |
9.3 |
M20x2 |
18 |
M2x0.4 |
1.6 |
M10x1 |
9 |
M20x2.5 |
17.5 |
M2.2x0.45 |
1.75 |
M10x1.25 |
8.8 |
M22x1 |
21 |
M2.5x0.45 |
2.05 |
M10x1.5 |
8.5 |
M22x1.5 |
20.5 |
M2.6x0.45 |
2.15 |
M11x1 |
10 |
M22x2 |
20 |
M3x0.35 |
2.65 |
M11x1.25 |
9.8 |
M22x2.5 |
19.5 |
M3x0.5 |
2.5 |
M11x1.5 |
9.5 |
M24x1 |
23 |
M3.5x0.35 |
3.15 |
M12x0.5 |
11.5 |
M24x1.5 |
22.5 |
M3.5x0.6 |
2.9 |
M12x0.75 |
11.3 |
M24x2 |
22 |
M4x0.5 |
3.5 |
M12x1 |
11 |
M24x3 |
21 |
M4x0.7 |
3.3 |
M12x1.25 |
10.3 |
M25x1.5 |
23.5 |
M4.5x0.5 |
4 |
M12x1.5 |
10.5 |
M25x2 |
23 |
M4.5x0.75 |
3.75 |
M12x1.75 |
10.3 |
M27x3 |
24 |
M5x0.5 |
4.5 |
M13x1 |
12 |
M30x3.5 |
26.5 |
M5x0.75 |
4.25 |
M14x1 |
13 |
M33x3.5 |
29.5 |
M5x0.8 |
4.2 |
M14x1.25 |
12.8 |
M36x4 |
32 |
M6x0.5 |
5.5 |
M14x1.5 |
12.5 |
M39x4 |
35 |
M6x0.75 |
5.25 |
M14x2 |
12 |
M42x4.5 |
37.5 |
M6x1 |
5 |
M15x1 |
14 |
M45x4.5 |
40.5 |
M7x0.5 |
6.5 |
M15x1.5 |
13.5 |
M48x5 |
43 |
M7x0.75 |
6.25 |
M16x1 |
15 |
M52x5 |
47 |
M7x1 |
6 |
M16x1.25 |
14.8 |
M56x5.5 |
50.5 |
M8x0.5 |
7.5 |
M16x1.5 |
14.5 |
M60x5.5 |
54.5 |
M8x0.75 |
7.25 |
M16x2 |
14 |
M64x6 |
58 |
M8x1 |
7 |
M18x1 |
17 |
M68x6 |
62 |
M8x1.25 |
6.8 |
M18x1.5 |
16.5 |
M72x6 |
66 |
UNC |
DRILL (MM) |
UNF |
DRILL (MM) |
---|---|---|---|
1.64 |
1.55 |
0.8 |
1.25 |
2.56 |
1.8 |
1.72 |
1.55 |
3.48 |
2.1 |
2.64 |
1.85 |
4.4 |
2.3 |
3.56 |
2.1 |
5.4 |
2.6 |
4.48 |
2.4 |
6.32 |
2.8 |
5.44 |
2.7 |
8.32 |
3.4 |
6.4 |
2.9 |
10.24 |
3.9 |
8.36 |
3.5 |
12.24 |
4.5 |
10.32 |
4.1 |
1/4.20 |
5.1 |
12.28 |
4.6 |
5/16.18 |
6.6 |
1/4.28 |
5.5 |
3/8.16 |
8 |
5/16.24 |
6.9 |
7/16.14 |
9.4 |
3/8.24 |
8.5 |
1/2.13 |
10.8 |
7/16.20 |
9.9 |
9/16.12 |
12.2 |
1/2.20 |
11.5 |
5/8.11 |
13.6 |
9/16.18 |
12.9 |
3/4.10 |
16.5 |
5/8.18 |
14.5 |
7/8.9 |
19.5 |
3/4.16 |
17.5 |
1”8 |
22.2 |
7/8.14 |
20.5 |
1.1/8.7 |
25 |
1”12 |
23.2 |
1.1/4.7 |
28.2 |
1.1/8.12 |
26.5 |
1.3/8.6 |
30.8 |
1.1/4.12 |
29.5 |
1.1/2.6 |
34 |
1.3/8.12 |
32.8 |
1.3/4.5 |
39.5 |
1.1/2.12 |
36 |
2”4.1/2 |
45.3 |
|
|
BSW |
DRILL (MM) |
BSF |
DRILL (MM) |
---|---|---|---|
1/8.40 |
2.54 |
3/16.32 |
3.97 |
3/16.24 |
3.7 |
1/4.26 |
5.37 |
1/4.20 |
5.08 |
5/16.22 |
6.8 |
5/16.18 |
6.5 |
3/8.20 |
8.3 |
3/8.16 |
7.9 |
7/16.18 |
9.7 |
7/16.14 |
9.3 |
1/2.16 |
11.1 |
1/2.12 |
10.6 |
9/16.16 |
12.7 |
9/16.12 |
12.2 |
5/8.14 |
14.1 |
5/8.11 |
13.6 |
11/16.14 |
15.6 |
3/4.10 |
16.5 |
3/4.12 |
16.9 |
13/16.10 |
18.1 |
13/16.12 |
18.5 |
7/8.9 |
19.4 |
7/8.11 |
19.9 |
15/16.9 |
21 |
1"10 |
22.9 |
1”8 |
22.2 |
1.1/8.9 |
25.8 |
1.1/8.7 |
24.9 |
1.1/4.9 |
28.9 |
1.1/4.7 |
28.1 |
1.3/8.8 |
31.8 |
1.3/8.6 |
30.7 |
1.1/2.8 |
34.9 |
1.1/2.6 |
33.9 |
1.5/8.8 |
38.1 |
1.5/8.5 |
36.2 |
1.3/4.7 |
40.8 |
1.3/4.5 |
39.4 |
1.7/8.7 |
44 |
1.7/8.4.1/2 |
42 |
2”7 |
47.2 |
2”4.1/2 |
45.2 |
|
|
BSP |
DRILL (MM) |
BSPT |
DRILL (MM) |
---|---|---|---|
1/16.28 |
6.8 |
1/16.28 |
6.2 |
1/8.28 |
8.8 |
1/8.28 |
8.2 |
1/4.19 |
11.8 |
1/4.19 |
10.9 |
3/8.19 |
15.3 |
3/8.19 |
14.5 |
1/2.14 |
19.1 |
1/2.14 |
18 |
5/8.14 |
21.1 |
3/4.14 |
23 |
3/4.14 |
24.6 |
1”11 |
29 |
7/8.14 |
28.4 |
1.1/4”11 |
38 |
1”11 |
30.9 |
1.1/2”11 |
44 |
1.1/8.11 |
35.6 |
2”11 |
55 |
1.1/4.11 |
39.6 |
2.1/2”11 |
71 |
1.3/8.11 |
42 |
3”11 |
83 |
1.1/2.11 |
45.5 |
|
|
1.3/4.11 |
51.4 |
|
|
2”11 |
57.3 |
|
|
2.1/4”11 |
63.4 |
|
|
2.1/2”11 |
72.9 |
|
|
2.3/4”11 |
79.2 |
|
|
3”11 |
85.6 |
|
|
METRIC |
DRILL (MM) |
UNC |
DRILL (MM) |
UNF |
DRILL (MM) |
---|---|---|---|---|---|
1.6x0.35 |
1.45 |
1.64 |
1.67 |
0.8 |
1.38 |
2x0.4 |
1.8 |
2.56 |
1.98 |
1.72 |
1.69 |
2.5x0.45 |
2.3 |
3.48 |
2.27 |
2.64 |
2 |
3x0.5 |
2.8 |
4.4 |
2.56 |
3.56 |
2.31 |
3.5x0.6 |
3.2 |
5.4 |
2.89 |
4.48 |
2.6 |
4x0.7 |
3.7 |
6.32 |
3.14 |
5.44 |
2.91 |
4.5x0.75 |
4.2 |
8.32 |
3.8 |
6.4 |
3.22 |
5x0.8 |
4.6 |
10.24 |
4.34 |
8.36 |
3.84 |
6x1 |
5.6 |
12.24 |
5.01 |
10.32 |
4.47 |
8x1.25 |
7.4 |
1/4.20 |
5.77 |
1/4.28 |
5.94 |
10x1.5 |
9.3 |
5/16.18 |
7.3 |
5/16.24 |
7.5 |
12x1.75 |
11.2 |
3/8.16 |
8.8 |
3/8.24 |
9 |
14x2 |
13.1 |
7/16.14 |
10.3 |
7/16.20 |
10.5 |
16x2 |
15.1 |
1/2.13 |
11.8 |
1/2.20 |
12.1 |
THREAD |
DRILL (MM) |
---|---|
0 |
5 |
1 |
4.4 |
2 |
3.9 |
3 |
3.4 |
4 |
2.95 |
5 |
2.6 |
6 |
2.25 |
7 |
2 |
8 |
1.75 |
9 |
1.5 |
10 |
1.35 |