ISO Metric Coarse Thread Specifications
Industry Standard: ISO 261 / ISO 965
ISO metric coarse threads are the most widely used general-purpose screw threads in the world. Defined by the ISO 261 and ISO 965 standards, they are characterized by their thread pitch and nominal diameter. Coarse threads have a larger pitch relative to fine threads, providing higher resistance to stripping and cross-threading in soft materials.
| Size | Ø Major (mm) | Pitch (mm) | Ø Pitch (mm) | Ø Minor (Ext) | Tap Drill (75%) | Stress Area (mm²) |
|---|---|---|---|---|---|---|
| M1 | 1.00 | 0.25 | 0.838 | 0.729 | 0.75 | 0.46 |
| M1.2 | 1.20 | 0.25 | 1.038 | 0.929 | 0.95 | 0.73 |
| M1.4 | 1.40 | 0.30 | 1.205 | 1.075 | 1.10 | 0.98 |
| M1.6 | 1.60 | 0.35 | 1.373 | 1.221 | 1.25 | 1.27 |
| M1.8 | 1.80 | 0.35 | 1.573 | 1.421 | 1.45 | 1.70 |
| M2 | 2.00 | 0.40 | 1.740 | 1.567 | 1.60 | 2.07 |
| M2.2 | 2.20 | 0.45 | 1.908 | 1.713 | 1.75 | 2.48 |
| M2.5 | 2.50 | 0.45 | 2.208 | 2.013 | 2.05 | 3.39 |
| M3 | 3.00 | 0.50 | 2.675 | 2.459 | 2.50 | 5.03 |
| M3.5 | 3.50 | 0.60 | 3.110 | 2.850 | 2.90 | 6.78 |
| M4 | 4.00 | 0.70 | 3.545 | 3.242 | 3.30 | 8.78 |
| M4.5 | 4.50 | 0.75 | 4.013 | 3.688 | 3.75 | 11.32 |
| M5 | 5.00 | 0.80 | 4.480 | 4.134 | 4.20 | 14.18 |
| M6 | 6.00 | 1.00 | 5.350 | 4.917 | 5.00 | 20.12 |
| M7 | 7.00 | 1.00 | 6.350 | 5.917 | 6.00 | 28.86 |
| M8 | 8.00 | 1.25 | 7.188 | 6.647 | 6.75 | 36.61 |
| M10 | 10.00 | 1.50 | 9.026 | 8.376 | 8.50 | 57.99 |
| M12 | 12.00 | 1.75 | 10.863 | 10.106 | 10.25 | 84.27 |
| M14 | 14.00 | 2.00 | 12.701 | 11.835 | 12.00 | 115.44 |
| M16 | 16.00 | 2.00 | 14.701 | 13.835 | 14.00 | 156.67 |
| M18 | 18.00 | 2.50 | 16.376 | 15.294 | 15.50 | 192.47 |
| M20 | 20.00 | 2.50 | 18.376 | 17.294 | 17.50 | 244.79 |
| M22 | 22.00 | 2.50 | 20.376 | 19.294 | 19.50 | 303.40 |
| M24 | 24.00 | 3.00 | 22.051 | 20.752 | 21.00 | 352.50 |
| M27 | 27.00 | 3.00 | 25.051 | 23.752 | 24.00 | 459.41 |
| M30 | 30.00 | 3.50 | 27.727 | 26.211 | 26.50 | 560.59 |
| M33 | 33.00 | 3.50 | 30.727 | 29.211 | 29.50 | 693.55 |
| M36 | 36.00 | 4.00 | 33.402 | 31.670 | 32.00 | 816.72 |
| M39 | 39.00 | 4.00 | 36.402 | 34.670 | 35.00 | 975.75 |
| M42 | 42.00 | 4.50 | 39.077 | 37.129 | 37.50 | 1120.91 |
| M45 | 45.00 | 4.50 | 42.077 | 40.129 | 40.50 | 1306.00 |
| M48 | 48.00 | 5.00 | 44.752 | 42.587 | 43.00 | 1473.15 |
| M52 | 52.00 | 5.00 | 48.752 | 46.587 | 47.00 | 1757.83 |
| M56 | 56.00 | 5.50 | 52.428 | 50.046 | 50.50 | 2030.02 |
| M60 | 60.00 | 5.50 | 56.428 | 54.046 | 54.50 | 2362.02 |
| M64 | 64.00 | 6.00 | 60.103 | 57.505 | 58.00 | 2675.97 |
| M68 | 68.00 | 6.00 | 64.103 | 61.505 | 62.00 | 3055.29 |
| M72 | 72.00 | 6.00 | 68.103 | 65.505 | 66.00 | 3459.74 |
| M76 | 76.00 | 6.00 | 72.103 | 69.505 | 70.00 | 3889.33 |
| M80 | 80.00 | 6.00 | 76.103 | 73.505 | 74.00 | 4344.05 |
| M85 | 85.00 | 6.00 | 81.103 | 78.505 | 79.00 | 4947.79 |
| M90 | 90.00 | 6.00 | 86.103 | 83.505 | 84.00 | 5590.80 |
| M95 | 95.00 | 6.00 | 91.103 | 88.505 | 89.00 | 6273.09 |
| M100 | 100.00 | 6.00 | 96.103 | 93.505 | 94.00 | 6994.64 |
Standard FAQs
What does "coarse" thread mean in metric sizes?
Metric coarse threads are the default pitch option for a given nominal diameter. For example, for an M8 bolt, the coarse pitch is 1.25 mm. If no pitch is specified on a metric fastener (e.g. just "M8"), it always refers to the coarse thread standard.
What is the thread angle for ISO metric threads?
All ISO metric threads (both coarse and fine) have a symmetrical V-thread profile with a 60-degree thread angle, as specified in the ISO 68-1 standard.