What size bit fits this screw?
The drive type tells you the shape. This tells you the number. Head size varies a little between makers, so where two are listed, try the larger one first — the biggest bit that seats fully is always the right one.
| Screw | Phillips | Pozidriv | Torx | Hex key | Flat |
|---|---|---|---|---|---|
| M1.2Glasses, watches, tiny connectors. | PH000 | — | T3 | 1.0 mm | 1.5 mm |
| M1.4Phone internals, hinges. | PH000 / PH00 | — | T4 | 1.3 mm | 1.5 mm |
| M1.6Laptop internals, camera plates. | PH00 | — | T5 | 1.5 mm | 2.0 mm |
| M2Laptop covers, drives, drones. | PH00 / PH0 | PZ0 | T6 | 1.5 mm | 2.5 mm |
| M2.5Laptop bottom covers, hard drives. | PH0 / PH1 | PZ1 | T8 | 2.0 mm | 3.0 mm |
| M3PC cases, enclosures, 3D printers. | PH1 | PZ1 | T10 | 2.5 mm | 3.5 mm |
| M4Brackets, appliances, machinery. | PH2 | PZ2 | T20 | 3.0 mm | 4.5 mm |
| M5Bikes, racks, VESA mounts. | PH2 | PZ2 | T25 | 4.0 mm | 5.5 mm |
| M6Furniture, frames, heavy brackets. | PH3 | PZ3 | T30 | 5.0 mm | 6.5 mm |
Why the wrong number strips the head
A bit one size too small only touches the very bottom of the recess, so all the force lands on a tiny amount of metal and it rounds out in a couple of turns. A bit one size too big will not sit down and cams straight out. If a bit rattles in the head, it is wrong.
Not sure of the drive type? →Gear for this job
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Precision bit set
The right bit is what stops rounded heads
Magnetic bit holder
Keeps tiny screws on the tip