Engineering Tables/Metric Threads

Nominal Diameter (mm) Choice Thread Pitch Series Tapping Drill (mm) Clearance Drills (mm)
Tight Fit Free Fit
1 1st 0.20 Fine 0.80 1.05 1.20
0.25 Coarse 0.75
1.1 2nd 0.20 Fine 0.90 1.15 1.30
0.25 Coarse 0.85
1.2 1st 0.20 Fine 1.00 1.30 1.50
0.25 Coarse 0.95
1.4 2nd 0.20 Fine 1.20 1.50 1.70
0.30 Coarse 1.10
1.6 1st 0.20 Fine 1.40 1.70 2.00
0.35 Coarse 1.25
1.8 2nd 0.20 Fine 1.60 1.90 2.20
0.35 Coarse 1.45
2 1st 0.25 Fine 1.75 2.20 2.60
0.40 Coarse 1.60
2.2 2nd 0.25 Fine 1.95 2.40 2.80
0.45 Coarse 1.75
2.5 1st 0.25 Fine 2.15 2.70 3.10
0.45 Coarse 2.05
3 1st 0.35 Fine 2.65 3.20 3.60
0.50 Coarse 2.50
3.5 2nd 0.35 Fine 3.15 3.70 4.20
0.60 Coarse 2.90
4 1st 0.50 Fine 3.50 4.30 4.80
0.70 Coarse 3.30
4.5 2nd 0.50 Fine 4.00 4.80 5.30
0.75 Coarse 3.70
5 1st 0.50 Fine 4.50 5.30 5.80
0.80 Coarse 4.20
5.5 3rd 0.50 Fine 5.00 5.80 6.40
6 1st 0.75 Fine 5.25 6.40 7.00
1.00 Coarse 5.00
7 2nd 0.75 Fine 6.25 7.40 8.00
1.00 Coarse 6.00
8 1st 0.75 Fine 7.25 8.40 10.00
1.00 Fine 7.50
1.25 Coarse 6.80
9 3rd 0.75 Fine 8.25 9.50 10.50
1.00 Fine 8.00
1.25 Coarse 7.80
10 1st 0.75 Fine 9.25 10.50 12.00
1.00 Fine 9.00
1.25 Fine 8.80
1.50 Coarse 8.50
11 3rd 0.75 Fine 10.25 12.00 13.00
1.00 Fine 10.00
1.50 Coarse 9.50
12 1st 1.00 Fine 11.00 13.00 15.00
1.25 Fine 10.75
1.50 Fine 10.50
2.00 Coarse 10.20
14 2nd 1.00 Fine 13.00 15.00 17.00
1.25 Fine 12.80
1.50 Fine 12.50
2.00 Coarse 12.00
15 3rd 1.00 Fine 14.00 16.00 18.00
1.50 Fine 13.50
16 1st 1.00 Fine 15.00 17.00 19.00
1.50 Fine 14.50
2.00 Coarse 14.00
17 3rd 1.00 Fine 16.00 18.00 20.00
1.50 Fine 15.50
18 2nd 1.00 Fine 17.00 19.00 21.00
1.50 Fine 16.50
2.00 Fine 16.00
2.50 Coarse 15.50
20 1st 1.00 Fine 19.00 21.00 24.00
1.50 Fine 18.50
2.00 Fine 18.00
2.50 Coarse 17.50
22 2nd 1.00 Fine 21.00 23.00 26.00
1.50 Fine 20.50
2.00 Fine 20.00
2.50 Coarse 19.50
24 1st 1.00 Fine 23.00 25.00 28.00
1.50 Fine 22.50
2.00 Fine 22.00
3.00 Coarse 21.00
25 3rd 1.00 Fine 24.00 26.00 30.00
1.50 Fine 23.50
2.00 Fine 23.00
26 3rd 1.00 Fine 24.50 27.00 31.00
27 2nd 1.00 Fine 26.00 28.00 32.00
1.50 Fine 25.50
2.00 Fine 25.00
3.00 Coarse 24.00
28 3rd 1.00 Fine 27.00 XX.00 XX.00
1.50 Fine 26.50
2.00 Fine 26.00
30 1st 1.00 Fine 29.00 31.00 35.00
1.50 Fine 28.50
2.00 Fine 28.00
3.00 Fine 27.00
3.50 Coarse 26.50
32 3rd 1.50 Fine 30.50 XX.00 XX.00
2.00 Fine 30.00
33 2nd 1.50 Fine 31.50 34.00 38.00
2.00 Fine 31.00
3.00 Fine 30.00
3.50 Coarse 29.50
35 3rd 1.50 Fine 33.50 XX.00 XX.00
2.00 Fine 33.00
36 1st 1.50 Fine 34.50 37.00 42.00
2.00 Fine 34.00
3.00 Fine 33.00
4.00 Coarse 32.00
38 3rd 1.50 Fine XX.50
39 2nd 1.50 Fine 37.50 40.00 45.00
2.00 Fine 37.00
3.00 Fine 36.00
4.00 Coarse 35.50
40 3rd 1.50 Fine 38.50
2.00 Fine 38.00
3.00 Fine 37.00
42 1st 1.50 Fine 40.50 43.00 48.00
2.00 Fine 40.00
3.00 Fine 39.00
4.00 Fine 38.00
4.50 Coarse 37.50
45 2nd 1.50 Fine 43.50 46.00 52.00
2.00 Fine 43.00
3.00 Fine 42.00
4.00 Fine 41.00
4.50 Coarse 40.50
48 1st 1.50 Fine 46.50 50.00 56.00
2.00 Fine 46.00
3.00 Fine 45.00
4.00 Fine 44.00
5.00 Coarse 43.00
50 3rd 1.50 Fine 48.50
2.00 Fine 48.00
3.00 Fine 47.00
52 2nd 1.50 Fine 50.50 54.00 62.00
2.00 Fine 50.00
3.00 Fine 49.00
4.00 Fine 48.00
5.00 Coarse 47.00
55 3rd 1.50 Fine 53.50
2.00 Fine 53.00
3.00 Fine 52.00
4.00 Fine 51.00
56 1st 1.50 Fine 54.50 58.00 66.00
2.00 Fine 54.00
3.00 Fine 53.00
4.00 Fine 52.00
5.50 Coarse 50.50
Notes:
  1. Nominal diameters, pitches, series and choices as specified in ISO 261.
  2. The Coarse Series is the preferred series. The Fine Series is to be used only when the Coarse Series is not suitable due to wall thickness or other space considerations.