Watch movement size converter
Convert watch movement diameters between lignes, the watchmakers’ unit, and millimeters or inches.
That's about the same as an ETA 2824 movement.
What it means
How large is that movement?
Movement (calibre) diameter, not the case. A case is usually several millimeters wider than its movement.
Every unit
That movement in every unit
Learn
Three things worth knowing
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× 2.256
Lignes × 2.256 = mm: 13‴ is 29.3 mm, 16½‴ is 37.2 mm.
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The French inch
The ligne comes from the pre-metric French pied du roi, kept by Swiss watchmaking after France went metric.
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Not the button ligne
Buttons also use “ligne”, but it is a fortieth of an inch, 0.635 mm.
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Popular movement conversions
Background
About lignes
Watchmakers size movements in lignes (‴), the old French line: a twelfth of the French inch, 2.2558 mm. 11½ lignes is 25.9 mm; the ETA 2824, one of the most used automatic movements, is sold as 11½‴ and measures 25.6 mm, since makers round to the nearest named size.