ISO Metric Thread Dimensions
Metric threads are manufactured according to strict specifications defined by the ISO standardisation authority to ensure cross-compatibility between mating components. The data below represents the dimensions of metric coarse machine screw threads as defined by ISO standards.
Please note that these figures relate to product design, and are always implemented with tolerances in mind. In practice, values related to tapping and drilling can vary significantly dependent on many factors such as material and operating temperature.
| Thread Size | Nominal Diameter (mm) | Core Diameter (mm) | Thread Pitch (mm) | Effective Diameter (mm) | Tapping Drill (mm) | Clearance Hole (mm) |
|---|---|---|---|---|---|---|
| M1.6 | 1.6 | 1.1706 | 0.35 | 1.373 | 1.25 | 2.0 |
| M1.8 | 1.8 | 1.3706 | 0.35 | 1.573 | 1.45 | 2.3 |
| M2 | 2.0 | 1.5092 | 0.40 | 1.740 | 1.60 | 2.6 |
| M2.2 | 2.2 | 1.6480 | 0.45 | 1.908 | 1.75 | 2.9 |
| M2.5 | 2.5 | 1.9480 | 0.45 | 2.208 | 2.05 | 3.1 |
| M3 | 3.0 | 2.3866 | 0.50 | 2.675 | 2.50 | 3.6 |
| M3.5 | 3.5 | 2.7638 | 0.60 | 3.110 | 2.90 | 4.2 |
| M4 | 4.0 | 3.1412 | 0.70 | 3.545 | 3.30 | 4.8 |
| M4.5 | 4.5 | 3.5798 | 0.75 | 4.013 | 3.80 | 5.3 |
| M5 | 5.0 | 4.0184 | 0.80 | 4.480 | 4.20 | 5.8 |
| M6 | 6.0 | 4.7732 | 1.00 | 5.350 | 5.00 | 7.0 |
| M7 | 7.0 | 5.7732 | 1.00 | 6.350 | 6.00 | 8.0 |
| M8 | 8.0 | 6.4664 | 1.25 | 7.188 | 6.80 | 10.0 |
| M10 | 10.0 | 8.1596 | 1.50 | 9.026 | 8.50 | 12.0 |
| M12 | 12.0 | 9.8530 | 1.75 | 10.863 | 10.20 | 15.0 |
| M14 | 14.0 | 11.5462 | 2.00 | 12.701 | 12.00 | 17.0 |
| M16 | 16.0 | 13.5462 | 2.00 | 14.701 | 14.00 | 19.0 |
| M18 | 18.0 | 14.9328 | 2.50 | 16.376 | 15.50 | 22.0 |
| M20 | 20.0 | 16.9328 | 2.50 | 18.376 | 17.50 | 24.0 |
| M22 | 22.0 | 18.9328 | 2.50 | 20.376 | 19.50 | 26.0 |
| M24 | 24.0 | 20.3194 | 3.00 | 22.051 | 21.00 | 28.0 |
| M27 | 27.0 | 23.3194 | 3.00 | 25.051 | 24.00 | 33.0 |
| M30 | 30.0 | 25.7060 | 3.50 | 27.727 | 26.50 | 35.0 |
| M33 | 33.0 | 28.7060 | 3.50 | 30.727 | 29.50 | 38 |
| M36 | 36.0 | 31.0924 | 4.00 | 33.402 | 32.00 | 41 |
| M39 | 39.0 | 34.0924 | 4.00 | 36.402 | 35.00 | 44 |
| M42 | 42.0 | 36.4790 | 4.50 | 39.077 | 37.50 | 47 |
| M45 | 45.0 | 39.4790 | 4.50 | 42.077 | 40.50 | 50 |
| M48 | 48.0 | 41.8646 | 5.00 | 44.752 | 43.00 | 53 |
| M52 | 52.0 | 45.8646 | 5.00 | 48.752 | 47.00 | 57 |
| M56 | 56.0 | 49.2522 | 5.50 | 52.428 | 50.50 | 61 |
| M60 | 60.0 | 53.2522 | 5.50 | 56.428 | 54.50 | 65 |
| M64 | 64.0 | 56.6388 | 6.00 | 60.103 | 58.00 | 69 |
| M68 | 68.0 | 60.6388 | 6.00 | 64.103 | 62.00 | 73 |
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