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Tapping Drill Sizes
General information
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.
Metric coarse and fine threads
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 and UNF threads
|
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 and BSF threads
|
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 and BSPT pipe threads
|
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 |
|
|
Tapping drills for fluteless taps
|
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 |
BA threads
|
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 |
