Watch case back screw (small cases) screw size
M1.2 · 1.7 mm long
If you are replacing a screw on Watch case back screw (small cases), the thread is M1.2, 1.7 mm long.
The record covers screw-down case back on smaller watches.
This entry is marked reported and comes from atime.com.au.
An M1.2 screw is 1.2 mm in diameter with a 0.25 mm pitch, tapped with a 0.95 mm drill; imperial look-alike: #0-80 UNF (1.52 mm) is the closest imperial screw, but it is bigger — not a substitute.
Watch case back screw (small cases) screw specifications
One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.
| Thread | Length | Pitch | Head | Drive | Where it goes | Status |
|---|---|---|---|---|---|---|
| M1.2 | 1.7 mm | 0.25 mm | not stated | not stated | screw-down case back on smaller watches | Reported |
Fitment records and sources
screw-down case back on smaller watches
pitch 0.25 mm · tap 0.95 mm · clearance 1.4 mm · PH000 / JIS 00 / Torx T1–T2
How to check the screw before you buy
- Phone and wearable screws are tiny and often differ by fractions of a millimetre between positions; keep each one next to the hole it came from.
- Diameter: across the threads an M1.2 screw measures about 1.2 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.25 mm from one thread crest to the next (40 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
- The record states 1.7 mm. Going longer risks bottoming out or touching parts behind the hole; going shorter loses thread engagement.
- Driver: the source does not name the drive. Standard M1.2 heads take PH000 / JIS 00 for Phillips and T1–T2 for Torx; a bit that fits loosely will cam out and strip the head.
- Tightening: no device-specific torque is published in these records. The site's general figure for M1.2 is about 5-8 N·cm into metal threads and 3-5 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M1.2
- M1.2 and M1.4 look identical in an eyeglass repair kit — the wrong one strips soft acetate or metal hinges.
More in Phones, Tablets & Wearables
Akuvox A08 video doorbellAkuvox A08 video doorbell (back plate)Anbernic RG35XX rear case screwsApple Watch case screwsApple Watch strap adapterASUS ROG Ally (RC71L)Asus ROG Ally (RC71L) back panel and M.2 2230 SSD coverASUS ROG Ally RC71L rear shellCompact smart sensor PCBsDive watch bezel insertDive watch bezelsExtech 407732 sound level meter battery cover screw
Browse all 134 in Phones, Tablets & Wearables →The same screw also fits
Devices whose records share a thread with Watch case back screw (small cases), closest length match first.
- Watch casebacks & bracelet links also M1.2 × 1.7 mm
- Watch dial foot / movement ring also M1.2 × 1.7 mm
- Smartphone antenna clips (some OEMs) also M1.2 × 1.7 mm
- Apple Watch strap adapter also M1.2 × 1.7 mm
- Wireless earbud charging cases also M1.2 × 1.7 mm
- Hearing aids also M1.2 × 1.7 mm
- Hearing aid battery door hinge also M1.2 × 1.7 mm
- Precision instruments (NBK/SAIDA style) also M1.2 × 1.7 mm
Questions about Watch case back screw (small cases) screws
- What size screw does Watch case back screw (small cases) use?
- M1.2 × 1.7 mm for screw-down case back on smaller watches.
- How long are the screws in Watch case back screw (small cases)?
- The record gives 1.7 mm. Measure the original from under the head (overall for a countersunk head) to confirm before ordering.
- What is the thread pitch of an M1.2 screw?
- 0.25 mm (coarse), which is the standard pitch for M1.2 machine screws. The tap drill is 0.95 mm and the normal clearance hole is 1.4 mm.
- What screwdriver do I need for Watch case back screw (small cases)?
- The sources do not name the drive. For M1.2, Phillips heads normally take PH000 / JIS 00 and Torx heads T1–T2.
- Can I use an imperial screw instead of M1.2?
- No. Imperial look-alike: #0-80 UNF (1.52 mm) is the closest imperial screw, but it is bigger — not a substitute. Use a true M1.2 screw so it does not cross-thread or strip the hole.