Longines Serial Numbers

Longines Serial Number Chart (1867 to 1980)

Serial milestones from the widely reproduced Longines movement-serial table, which runs to 15 million in 1969, and the 50-million series that followed it through 1980. Nothing public covers the numbers after that; the St-Imier archive can confirm any specific watch.

Where to Find Your Longines Serial Number

On vintage Longines the production serial is on the movement, engraved on a plate or bridge — and on very early calibers it can sit under the dial. You'll usually need to open the caseback (or have a watchmaker do it) to read it.

On more recent wristwatches an 8-digit serial appears on the outside of the caseback and is the number Longines references in its records. Pocket watches typically carry numbers inside the case back and on the movement.

From the mid-1940s a 4-digit reference number began appearing on case backs (often in the 5000–6000 range), identifying the model rather than the individual watch.

Where to look, line by line:

• Vintage chronographs (13ZN, 30CH) and the time-only calibers of the 1930s to 1960s (12.68Z, 27M, 30L): serial engraved on the movement, usually on the barrel bridge or the plate under the balance; the caliber is stamped nearby. Inside the caseback: the reference (four digits from the mid-1940s), a case number that is not the serial, and the winged-hourglass Longines mark.
• Conquest (1954 on), Flagship (1957 on), Admiral and Ultra-Chron: same arrangement, movement serial inside, reference and case number in the back. Conquest and Flagship casebacks carry their enamel or relief medallions on the outside.
• US-market watches, 1920s to 1960s: the movement is stamped LXW (Longines-Wittnauer, the American importer) beside the serial, and the case is often American-made, signed by the case maker rather than Longines. That is correct for a US delivery, not a sign of a swap.
• Modern Longines (roughly 1990 on): an eight-digit serial engraved on the outside of the caseback, repeated on the warranty card, with the L-prefix reference (L2.673.4.78.3 and so on) beside it. The archive dates these too.

How to Read a Longines Serial Number

Longines serials are simple consecutive numbers — typically six to eight digits — that increase over time, with no embedded year code. You date a watch by matching the serial to a chart, then ideally confirming with the archive.

Anchors worth remembering: 100,000 is the mid-1870s, one million lands around 1899, five million is 1931, ten million is 1957 and fifteen million is 1969. Then the series jumps: from 1970 Longines numbered movements in the 50 millions, from about 50.8 million in 1970 to 54.9 million in 1980, and the public table ends there. Nothing sits between 15 and 50 million in the movement series, so a number in that gap on the outside of a caseback is a modern eight-digit serial, not a 1970s or 1980s movement number.

Two things the chart cannot do. It dates the movement, which Longines often cased and invoiced later, sometimes by a year or more; the archive gives the invoice date, which is the one that matters. And it says nothing about the model: the same run of numbers went into chronographs, Conquests and dress watches alike. For anything after 1980, or anything important, lean on St-Imier for certainty.

Reference and Caliber Numbers

From the mid-1940s, Longines marked case backs with 4-digit reference numbers (commonly 5000–6000) identifying the case design and dial layout; many watches share one reference but each has its own serial. Later references became longer alphanumeric strings (e.g. L4.xxxxx) used for catalog and warranty identification.

Caliber designations — 13ZN, 30L, L990 and the like — are stamped on the movement and identify the movement family and architecture. The St‑Imier archive ties serial, caliber, and reference together to reconstruct a watch's original specification.

Is Your Longines Real? What the Serial Can and Cannot Tell You

Longines is the one brand on this site where the archive settles the question directly. Send the serial to St-Imier and the heritage department answers with the caliber, the reference, the invoice date and the country or agent the watch was delivered to; the emailed reply has long been free, the printed Extract from the Archives is CHF 120 (for watches over ten years old, four to five weeks), and a Certificate of Authenticity, for which the watch goes to Switzerland for a watchmaker's examination, is CHF 300 and about three months. The Extract, in Longines' own words, does not certify the authenticity of the watch or its components; it tells you what left the factory under that number.

That makes the check a matching exercise. The caliber stamped on the movement should be the one the archive names; the reference inside the caseback should match; the dial should be the layout the reference carried; and, for a US-delivered watch, the LXW stamp and an American case are correct rather than suspicious. The engraving should be fine and even, cut in the same hand as the caliber number beside it. A serial that decodes to 1938 on a movement stamped 30CH (a 1947 caliber), or a 13ZN in a case whose reference the archive places in the 1960s, is a marriage of parts.

The dial is where most of the trouble is. Longines redials are common and often good, and the serial cannot help you there; the archive can, if the reference it names carried a different dial. Our frankenwatch guide covers what to look for on the dial side. The step that settles everything is a watchmaker who knows the caliber with the caseback off, and every Longines sold on Grey Market goes through that inspection before the seller is paid.

What the Serial Says About Value

On a vintage Longines the year and the caliber are most of the price, and the serial gives you both. A 13ZN chronograph in the 5 to 7 millions sits in a different market from a 30CH in the 9 millions that looks the same across a room; a first-series Conquest or Flagship from the 1950s carries a premium over the 1960s examples; a 1960 Legend Diver ref. 7042 in the 11 millions is the collectible one, and the 2007 re-edition is priced as the modern watch it is. The archive answer that comes with the serial is what turns a nice old Longines into a documented one, and documented examples sell for more.

Within a year and caliber, originality decides the rest, and again the archive is the tool: a dial and reference that match the Extract, a case with the right maker's marks for its market and a caliber the archive confirms are what a full-provenance vintage Longines is priced on. If the watch is one you might sell, request the archive reply before you list it; it costs nothing, and it is the first thing a serious buyer will ask to see.

Frequently asked questions