ISO 261ISO 26260° flank
ISO Metric Threads
The global default for machine screws and bolts. Diameter and pitch are both in millimetres, and the designation carries the pitch whenever it is not the coarse one — M10 × 1.25 is a fine pitch, plain M10 is coarse. 82 designations are listed here, all quoted in millimetres.
Dimensions82 sizes
| Designation | Pitch (mm) | Major (mm) | Pitch Ø (mm) | Minor ext (mm) | Tap drill (mm) |
|---|---|---|---|---|---|
| M1 × 0.25 | 0.25 | 1 | 0.84 | 0.69 | 0.75 |
| M1 × 0.2 fine | 0.2 | 1 | 0.87 | 0.75 | 0.8 |
| M1.2 × 0.25 | 0.25 | 1.2 | 1.04 | 0.89 | 0.95 |
| M1.2 × 0.2 fine | 0.2 | 1.2 | 1.07 | 0.95 | 1 |
| M1.4 × 0.3 | 0.3 | 1.4 | 1.21 | 1.03 | 1.1 |
| M1.4 × 0.2 fine | 0.2 | 1.4 | 1.27 | 1.15 | 1.2 |
| M1.6 × 0.35 | 0.35 | 1.6 | 1.37 | 1.17 | 1.25 |
| M1.6 × 0.2 fine | 0.2 | 1.6 | 1.47 | 1.35 | 1.4 |
| M1.8 × 0.35 | 0.35 | 1.8 | 1.57 | 1.37 | 1.45 |
| M1.8 × 0.2 fine | 0.2 | 1.8 | 1.67 | 1.55 | 1.6 |
| M2 × 0.4 | 0.4 | 2 | 1.74 | 1.51 | 1.6 |
| M2 × 0.25 fine | 0.25 | 2 | 1.84 | 1.69 | 1.75 |
| M2.2 × 0.45 | 0.45 | 2.2 | 1.91 | 1.65 | 1.75 |
| M2.5 × 0.45 | 0.45 | 2.5 | 2.21 | 1.95 | 2.05 |
| M2.5 × 0.35 fine | 0.35 | 2.5 | 2.27 | 2.07 | 2.15 |
| M3 × 0.5 | 0.5 | 3 | 2.68 | 2.39 | 2.5 |
| M3 × 0.35 fine | 0.35 | 3 | 2.77 | 2.57 | 2.65 |
| M3.5 × 0.6 | 0.6 | 3.5 | 3.11 | 2.76 | 2.9 |
| M3.5 × 0.35 fine | 0.35 | 3.5 | 3.27 | 3.07 | 3.15 |
| M4 × 0.7 | 0.7 | 4 | 3.55 | 3.14 | 3.3 |
| M4 × 0.5 fine | 0.5 | 4 | 3.68 | 3.39 | 3.5 |
| M4.5 × 0.75 | 0.75 | 4.5 | 4.01 | 3.58 | 3.75 |
| M4.5 × 0.5 fine | 0.5 | 4.5 | 4.18 | 3.89 | 4 |
| M5 × 0.8 | 0.8 | 5 | 4.48 | 4.02 | 4.2 |
| M5 × 0.5 fine | 0.5 | 5 | 4.68 | 4.39 | 4.5 |
| M5.5 × 0.9 | 0.9 | 5.5 | 4.92 | 4.4 | 4.6 |
| M6 × 1 | 1 | 6 | 5.35 | 4.77 | 5 |
| M6 × 0.75 fine | 0.75 | 6 | 5.51 | 5.08 | 5.25 |
| M7 × 1 | 1 | 7 | 6.35 | 5.77 | 6 |
| M7 × 0.75 fine | 0.75 | 7 | 6.51 | 6.08 | 6.25 |
| M8 × 1.25 | 1.25 | 8 | 7.19 | 6.47 | 6.75 |
| M8 × 1 fine | 1 | 8 | 7.35 | 6.77 | 7 |
| M8 × 0.75 fine | 0.75 | 8 | 7.51 | 7.08 | 7.25 |
| M9 × 1.25 | 1.25 | 9 | 8.19 | 7.47 | 7.75 |
| M9 × 1 fine | 1 | 9 | 8.35 | 7.77 | 8 |
| M10 × 1.5 | 1.5 | 10 | 9.03 | 8.16 | 8.5 |
| M10 × 1.25 fine | 1.25 | 10 | 9.19 | 8.47 | 8.75 |
| M10 × 1 fine | 1 | 10 | 9.35 | 8.77 | 9 |
| M11 × 1.5 | 1.5 | 11 | 10.03 | 9.16 | 9.5 |
| M11 × 1 fine | 1 | 11 | 10.35 | 9.77 | 10 |
| M12 × 1.75 | 1.75 | 12 | 10.86 | 9.85 | 10.25 |
| M12 × 1.5 fine | 1.5 | 12 | 11.03 | 10.16 | 10.5 |
| M12 × 1.25 fine | 1.25 | 12 | 11.19 | 10.47 | 10.75 |
| M14 × 2 | 2 | 14 | 12.7 | 11.55 | 12 |
| M14 × 1.5 fine | 1.5 | 14 | 13.03 | 12.16 | 12.5 |
| M16 × 2 | 2 | 16 | 14.7 | 13.55 | 14 |
| M16 × 1.5 fine | 1.5 | 16 | 15.03 | 14.16 | 14.5 |
| M18 × 2.5 | 2.5 | 18 | 16.38 | 14.93 | 15.5 |
| M18 × 2 fine | 2 | 18 | 16.7 | 15.55 | 16 |
| M18 × 1.5 fine | 1.5 | 18 | 17.03 | 16.16 | 16.5 |
| M20 × 2.5 | 2.5 | 20 | 18.38 | 16.93 | 17.5 |
| M20 × 2 fine | 2 | 20 | 18.7 | 17.55 | 18 |
| M20 × 1.5 fine | 1.5 | 20 | 19.03 | 18.16 | 18.5 |
| M22 × 2.5 | 2.5 | 22 | 20.38 | 18.93 | 19.5 |
| M22 × 2 fine | 2 | 22 | 20.7 | 19.55 | 20 |
| M22 × 1.5 fine | 1.5 | 22 | 21.03 | 20.16 | 20.5 |
| M24 × 3 | 3 | 24 | 22.05 | 20.32 | 21 |
| M24 × 2 fine | 2 | 24 | 22.7 | 21.55 | 22 |
| M27 × 3 | 3 | 27 | 25.05 | 23.32 | 24 |
| M27 × 2 fine | 2 | 27 | 25.7 | 24.55 | 25 |
| M30 × 3.5 | 3.5 | 30 | 27.73 | 25.71 | 26.5 |
| M30 × 2 fine | 2 | 30 | 28.7 | 27.55 | 28 |
| M33 × 3.5 | 3.5 | 33 | 30.73 | 28.71 | 29.5 |
| M33 × 3 fine | 3 | 33 | 31.05 | 29.32 | 30 |
| M36 × 4 | 4 | 36 | 33.4 | 31.09 | 32 |
| M36 × 3 fine | 3 | 36 | 34.05 | 32.32 | 33 |
| M39 × 4 | 4 | 39 | 36.4 | 34.09 | 35 |
| M39 × 3 fine | 3 | 39 | 37.05 | 35.32 | 36 |
| M42 × 4.5 | 4.5 | 42 | 39.08 | 36.48 | 37.5 |
| M42 × 3 fine | 3 | 42 | 40.05 | 38.32 | 39 |
| M45 × 4.5 | 4.5 | 45 | 42.08 | 39.48 | 40.5 |
| M45 × 3 fine | 3 | 45 | 43.05 | 41.32 | 42 |
| M48 × 5 | 5 | 48 | 44.75 | 41.87 | 43 |
| M48 × 3 fine | 3 | 48 | 46.05 | 44.32 | 45 |
| M52 × 5 | 5 | 52 | 48.75 | 45.87 | 47 |
| M52 × 4 fine | 4 | 52 | 49.4 | 47.09 | 48 |
| M56 × 5.5 | 5.5 | 56 | 52.43 | 49.25 | 50.5 |
| M56 × 4 fine | 4 | 56 | 53.4 | 51.09 | 52 |
| M60 × 5.5 | 5.5 | 60 | 56.43 | 53.25 | 54.5 |
| M60 × 4 fine | 4 | 60 | 57.4 | 55.09 | 56 |
| M64 × 6 | 6 | 64 | 60.1 | 56.64 | 58 |
| M64 × 4 fine | 4 | 64 | 61.4 | 59.09 | 60 |