Home › Threads & Fasteners › Metric Chart
Metric Thread Chart (ISO M)
ISO 261 metric coarse threads with full dimensions in millimeters.
ISO Metric Coarse Thread Dimensions (mm)
| Thread | Pitch P | Pitch dia d₂ | Minor dia (bolt) | Tap drill |
|---|---|---|---|---|
| M1.6 | 0.35 | 1.373 | 1.221 | 1.25 |
| M2 | 0.4 | 1.740 | 1.567 | 1.6 |
| M2.5 | 0.45 | 2.208 | 2.013 | 2.05 |
| M3 | 0.5 | 2.675 | 2.459 | 2.5 |
| M4 | 0.7 | 3.545 | 3.242 | 3.3 |
| M5 | 0.8 | 4.480 | 4.134 | 4.2 |
| M6 | 1.0 | 5.350 | 4.917 | 5.0 |
| M8 | 1.25 | 7.188 | 6.647 | 6.8 |
| M10 | 1.5 | 9.026 | 8.376 | 8.5 |
| M12 | 1.75 | 10.863 | 10.106 | 10.2 |
| M16 | 2.0 | 14.701 | 13.835 | 14.0 |
| M20 | 2.5 | 18.376 | 17.294 | 17.5 |
| M24 | 3.0 | 22.051 | 20.752 | 21.0 |
| M30 | 3.5 | 27.727 | 26.211 | 26.5 |
| M36 | 4.0 | 33.402 | 31.670 | 32.0 |
| M42 | 4.5 | 39.077 | 37.129 | 37.5 |
| M48 | 5.0 | 44.752 | 42.587 | 43.0 |
| M64 | 6.0 | 60.103 | 57.505 | 58.0 |
FAQ
What is pitch diameter?
The imaginary diameter where thread width equals groove width — the mating reference size.
How is minor diameter calculated?
d − 1.0825 × P for external metric threads, approximately.