(*) Lignes
🧭 What does “lignes” mean?
“Ligne” (plural: lignes) is an old French unit of measurement traditionally used in the watchmaking industry to indicate the diameter of a watch movement.
📏 Conversion:
- 1 ligne = 2.2558 mm
- So for example:
11½ lignes × 2.2558 mm ≈ 25.44 mm
(often rounded up to 25.6 mm depending on source)
📌 Why is it used?
- This unit dates back to classical European watchmaking, especially in Switzerland and France.
- Many movement manufacturers still list movement sizes in lignes, especially in technical or traditional contexts, even though millimeters are now more common.
- It helps quickly categorize movement sizes:
- 6¾ ligne → for small ladies’ movements
- 11½ ligne → standard size for men’s movements
- 13¼ ligne → for larger movements like chronographs (e.g., ETA 7750)
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🔧 In Practice:
You’ll sometimes find movement or dial sizes listed in lignes, especially on datasheets, vintage documentation, or technical watchmaker resources — so it’s useful to know the conversion.
