Zenith is one of the few Swiss manufactures to have made its own movements without a break since the nineteenth century. The table below covers what has been documented so far rather than everything the firm built: the hand-wound competition calibres entered in the observatory chronometry trials, the automatics of the classic period, and El Primero, the high-frequency automatic chronograph of 1969 that came to define the brand. Click any calibre number for its own page.
| Calibre | Type | Jewels | Frequency | Years | Key note |
|---|---|---|---|---|---|
| 135 | Hand-wound | 18 | 18,000 vph | Mid-20th century | Built for the observatory chronometry trials |
| 146 | Hand-wound | 17 | 18,000 vph | Mid-20th century | Small, and meant for dress watches |
| 2542 | Automatic | 25 | 21,600 vph | Classic era | The automatic that came before El Primero |
| 400 / 3019 PHC | Automatic chronograph | 31 | 36,000 vph | From 1969 | El Primero — the one that changed the rules |
How to identify a vintage Zenith
The calibre number is engraved on the movement bridge. Watch out with El Primero: 3019 PHC is the original 1969 factory reference and 400 a later one from the same family, so seeing one number rather than the other does not mean you are looking at a different movement. Always check the engraved number against the case reference.