Watch screwdrivers are the smallest drivers most people will ever use. A movement screw inside a mechanical watch can be under 1 mm across - requiring a perfectly ground flat blade and a steady hand.
Jewelers Screwdriver Sizes
Watchmaker screwdrivers are almost exclusively flat blade (slotted), sized by blade width:
| Blade Width | Typical Use |
|---|---|
| 0.6 mm | Movement screws, hairspring studs |
| 0.8 mm | Movement screws, dial feet |
| 1.0 mm | Small plate screws, movement clamps |
| 1.2 mm | Case clamps, movement holders |
| 1.4 mm | Case back screws, strap bar screws |
| 1.6 mm | Bracelet screws, larger case screws |
| 2.0 mm | Bracelet links, band pin screws |
Watchmaker vs Generic Precision Sets
A generic precision screwdriver set from a hardware store includes Phillips, Torx, and hex bits alongside a few flat blades. A proper watchmaker set is different:
- All flat blade - watchmaking uses almost no Phillips or Torx screws
- Swivel cap on top - allows the handle to spin freely under fingertip pressure
- Replaceable blades - ground to exact widths, replaced when chipped
- Anti-magnetic steel - standard steel blades magnetise watch components and ruin timekeeping
- Fine increments - 0.2 mm steps between sizes rather than the 0.5 mm jumps in generic sets
Case Back Removal
Screwdriver-style case backs have 4 to 8 small flat head screws around the perimeter. You remove these with a 1.2–1.6 mm flat blade. However, most modern watches use snap-off or screw-down case backs - these require a case opener tool (a friction ball or a notched wrench), not a screwdriver. Do not try to pry a snap-off case back with a screwdriver blade - you will scratch the case and potentially damage the gasket.
Band and Bracelet Adjustment
Many metal watch bracelets use tiny screws to hold individual links. These are typically 1.4–1.6 mm flat head screws. Some use push pins instead - which need a pin pusher, not a screwdriver. Check your bracelet links from the side: if you see a screw slot, use a screwdriver; if you see a smooth pin end, use a pin pusher.
Keep your watch screwdrivers demagnetised. Run them across a demagnetiser tool before working on any mechanical movement. A magnetised screwdriver blade can magnetise the balance spring and cause the watch to gain minutes per day.
Related Guides
Precision Screwdriver Sets: What to Look For
What to look for when buying a precision screwdriver set for electronics, phones, and small device repair.
Types of Screwdrivers: The Complete Guide
From Phillips to Torx, flat head to hex - every screwdriver type explained with sizes, uses, and selection tips.