M2 vs M3
They differ by 1.0 mm across the threads — enough that they are never interchangeable, but little enough that they are easy to mix up in a parts tray.
| M2 | M3 | |
|---|---|---|
| Thread diameter | 2.00 mm | 3.00 mm |
| Standard pitch | 0.4 mm | 0.5 mm |
| Tap drill | 1.6 mm | 2.5 mm |
| Clearance hole | 2.4 mm | 3.4 mm |
| Cap head Ø | 3.8 mm | 5.5 mm |
| Hex key | 1.5 mm | 2.5 mm |
| Torque into steel | 25-40 N·cm | 80-130 N·cm |
| Into plastic | 12-20 N·cm | 35-60 N·cm |
M2 is normally used for
Laptop bottom covers, SSD brackets, cameras, drones, small enclosures
Everything M2 fits →M3 is normally used for
PC cases, 2.5in drives, 3D printers, extrusion hardware, DIN-rail devices, robotics
Everything M3 fits →If you are not sure which one you have
Measure across the outside of the threads with a caliper. A reading within about 0.1 mm of the nominal size is your answer — 2.0 mm means M2, 3.0 mm means M3.
Use the screw size finder →Buy either size
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M2 screws
Assorted lengths in one box
M3 screws
Assorted lengths in one box
Digital caliper
Tells the two sizes apart for certain