Ligne ↔ millimetre converter
Movement sizes are traditionally measured in lignes, not millimetres. Enter either value below — the other updates instantly.
Uses the standard trade conversion of 1 ligne = 2.2558mm. Suppliers round slightly differently, so treat the result as a close estimate rather than an exact spec.
Why lignes?
The ligne — from the old French inch — has been the watch industry's standard movement-sizing unit since the pocket-watch era, and it stuck. Most movement spec sheets still quote size in lignes before millimetres, so converting between the two is one of the most common small calculations on a watchmaker's bench.