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Production dating

Serial number check

Enter the number engraved on the case or movement to see when it was issued. The checker covers 11 brands on one page; the table below shows which number each one reads and which years it can date.

Check a serial number

Where to look: Between the lugs at 6 o’clock once the bracelet is removed; on the inner bezel rehaut from the mid-2000s.

Try

What is covered

11 of the catalogue’s main brands can be checked. Brands whose numbers cannot be dated reliably are listed as not covered rather than guessed.

Covered
6
Partial
5
Not covered
4
BrandStatusNumber readPeriodWindow
RolexCoveredCase serial1926–20121–5 years
OmegaCoveredMovement serial1894–19991–8 years
SeikoCoveredCase serial1960s–1990sMonth, with the decade to confirm
LonginesCoveredMovement serial1867–19681–8 years
IWCCoveredMovement number1885–19711–10 years
Universal GenèveCoveredMovement serial1930–19721–7 years
Patek PhilippePartialMovement number1839–19255–10 years
HeuerPartialCase serial1962–19752–5 years
Audemars PiguetPartialCase number1972–19931–13 years
Vacheron ConstantinPartialMovement number1925–19703–10 years
ZenithPartialMovement number1915–19632–11 years
TudorNot coveredCase serial——
Jaeger-LeCoultreNot coveredMovement number——
CartierNot coveredCase number——
A. Lange & SöhneNot coveredMovement and case numbers——

Brand by brand

RolexCovered

Numeric serials from 1926 to mid-1987 are placed in a one- or two-year window; the single-letter prefixes used from 1987 to about 2010 map to a window of one to three years. Eight-character random serials from 2010 cannot be dated from the number.

  • Windows are approximate. A boundary between two years can shift by up to a year, so each window covers both possible years.
  • The sequence reached 999,999 around 1953 and restarted, so a number below 1,000,000 has two possible windows. The caseback date code and the movement settle it.
  • Numbers from 4,260,000 to 5,007,999 are associated with service replacement cases from around 1976 and are not dated.
  • The serial dates the case. The watch may have been assembled, sold or re-cased later.
Number read
Case serial
Where it is engraved
Between the lugs at 6 o’clock once the bracelet is removed; on the inner bezel rehaut from the mid-2000s.
Period · window
1926–2012 · 1–5 years
OmegaCovered

Each million-block of movement numbers maps to a year window. Windows are a single year through most of the 1960s and 1970s and wider before 1950 and after 1980.

  • Speedmaster movements from 1957 onward follow a separate sequence and are not covered.
  • Dates for the 1980s and 1990s blocks are less certain than earlier ones; read them as approximate. An Extract of the Archives from Omega gives the recorded delivery date.
  • After the 1920s the case number rarely matches the movement number; read the movement. From the 50,000,000 block the number may identify the finished watch rather than the movement.
Number read
Movement serial
Where it is engraved
Engraved on the movement, visible with the caseback removed. The case number is a different sequence.
Period · window
1894–1999 · 1–8 years
SeikoCovered

Seiko encodes the date: the first digit is the last digit of the year, the second the month (1–9, then 0 for October, N for November, D for December), the rest a production sequence. The check decodes month and year digit and lists each decade the year could fall in; the calibre on the caseback fixes the decade.

  • The serial never states the decade. Use the calibre (the first four digits of the case number) and the model’s production span to pick the right one.
  • Some seven-digit serials and modern Seiko 5 Sports models follow other rules.
  • A plausible decode shows the caseback is consistent with the scheme. It does not authenticate the watch.
Number read
Case serial
Where it is engraved
On the caseback next to the case number; six digits for most watches from the late 1960s, seven digits on earlier and some later pieces.
Period · window
1960s–1990s · Month, with the decade to confirm
LonginesCovered

Longines issued movement numbers in one sequence from 1867. The check places a number in the window for its block, up to 15,000,000 in 1969.

  • Boundaries can shift by up to a year, and movements were often cased some time after numbering.
  • Numbers from 15,000,000 (1969) cannot be dated from the number. Longines’ heritage department issues extracts from its registers for individual watches.
Number read
Movement serial
Where it is engraved
Engraved on the movement; a solid caseback must be opened. The case and reference numbers are separate.
Period · window
1867–1968 · 1–8 years
IWCCovered

IWC movement numbers follow the factory’s production records. The check uses decade blocks before 1940 and blocks of one to six years after.

  • The number was allocated when a batch of rough movements was laid down, sometimes well before the movement was finished and cased.
  • Numbers above 2,113,000 (after 1971) cannot be dated from the number.
  • IWC does not publish production records and says its archives are unreliable before 1885; its museum can research a specific watch.
Number read
Movement number
Where it is engraved
Engraved on the movement. The case number is a separate sequence and cannot be read here.
Period · window
1885–1971 · 1–10 years
Universal GenèveCovered

Movement serials from 500,000 to 3,000,000 map to windows of one to seven years.

  • Most of the company’s archives were lost, so windows are approximate; dates after 1943 are firmer than those before.
  • Numbers above 3,000,000 (after about 1972) are not reliably dated.
Number read
Movement serial
Where it is engraved
Engraved on the movement. Case reference numbers are a separate four- or five-digit sequence.
Period · window
1930–1972 · 1–7 years
Patek PhilippePartial

Movement numbers were sequential until the mid-1920s and can be dated from the number. From about 1930 Patek issued numbers in calibre blocks that can span decades, so later numbers are not datable from the number alone.

  • A block such as 860,000–869,999 covers watches recorded from 1935 to 1984. Only the Extract from the Archives gives the recorded production and sale dates.
  • Early windows span five to ten years, and individual watches do not always fall where their number suggests.
Number read
Movement number
Where it is engraved
Engraved on the movement; the case number is inside the caseback and is a different sequence.
Period · window
1839–1925 · 5–10 years
HeuerPartial

These chronographs share one case-serial sequence. Serials from 48,600 to 59,999 and from 82,500 to 276,999 map to windows of two to five years, from about 1962 to 1975. Other serials cannot be dated from the number.

  • The serial dates the case batch. Cases were sometimes assembled with dials and movements years later, so a watch can be later than its window.
  • Heuer reused five-digit numbers before 1962, so the check applies only to the chronograph lines introduced from 1962. Bundeswehr chronographs and dashboard timers have their own numbering.
  • Serials from 60,000 to 82,499, and from 277,000, cannot be dated from the number. TAG Heuer letter-prefixed serials from 1985 carry no date.
Number read
Case serial
Where it is engraved
On the caseback of Heuer chronographs from 1962 on: Autavia, Carrera, Camaro, Monaco, Skipper and the military Carreras.
Period · window
1962–1975 · 2–5 years
Audemars PiguetPartial

Audemars Piguet numbered cases per reference, so the number dates a watch only together with its reference. The check matches the reference and series number against the series ranges recorded in this catalogue, currently the Royal Oak 5402 (A to D series and gold executions) and the first Royal Oak Offshore 25721 casebacks.

  • Only references with recorded series ranges can be dated; others return no result rather than a guess.
  • Series years can shift by a year or two (B 1974–1977, C 1975–1980, D 1976–1985), so read a result as approximate.
  • Audemars Piguet’s heritage department confirms individual watches from its registers.
Number read
Case number
Where it is engraved
The series number engraved on the caseback: for the steel Royal Oak 5402 a letter A, B, C or D followed by up to four digits. Audemars Piguet’s separate case number, which also carries a letter prefix in some years, is a different sequence and is not read here.
Period · window
1972–1993 · 1–13 years
Vacheron ConstantinPartial

Movement numbers from 400,000 to 416,999 (about 1925–1934) and from 488,000 to 599,999 (about 1949–1970) map to year windows. Other numbers cannot be dated from the number.

  • Movement numbers rise in one sequence but were issued in calibre batches. Chronograph, calendar and repeater movements could stay in stock for years, so windows fit time-only watches best.
  • Numbers from 417,000 to 487,999, and from 600,000, cannot be dated from the number.
  • Vacheron Constantin’s heritage department certifies individual pieces from the original registers.
Number read
Movement number
Where it is engraved
Engraved on the movement. The case number is a separate, slower sequence and is not read here.
Period · window
1925–1970 · 3–10 years
ZenithPartial

Swiss Zenith movement numbers from 2,000,000 to 5,609,999 map to windows of two to eleven years, from about 1915 to 1963. Earlier and later numbers, and French-made movements, cannot be dated from the number.

  • A window marks when a batch of movements was numbered; some batches were finished years later.
  • Five- and six-digit numbers belong to French (Besançon) movements, which used their own numbering. Seven-digit numbers from about 7,000,000 upward are usually case numbers.
  • Most movements stopped carrying numbers in the late 1960s, and El Primero movements have none.
  • Zenith’s heritage department confirms individual watches from its archives.
Number read
Movement number
Where it is engraved
Engraved on the movement of Swiss-made Zenith movements. The case number is a separate, higher sequence and is not read here.
Period · window
1915–1963 · 2–11 years
TudorNot covered

Tudor serials cannot be placed reliably: year boundaries are uncertain by up to 200,000 numbers, the sequence restarted in the mid-1980s, and serials became random after 2002.

  • Date a Tudor from its reference, movement and dial details, or through Tudor’s service network.
Number read
Case serial
Where it is engraved
Between the lugs at 6 o’clock, like Rolex.
Jaeger-LeCoultreNot covered

Jaeger-LeCoultre assigned movement numbers in calibre blocks rather than one sequence, so the same number can belong to watches made twenty years apart. The manufacture’s archive extract is the reliable route.

Number read
Movement number
Where it is engraved
Engraved on the movement.
CartierNot covered

Cartier case numbers do not follow a date sequence. Dating relies on reference, hallmarks, movement and dial execution.

Number read
Case number
Where it is engraved
On the caseback, with the reference number.
A. Lange & SöhneNot covered

The modern manufacture (from 1994) does not number in a datable sequence. Dating is by reference and edition; Lange confirms individual watches on request.

Number read
Movement and case numbers
Where it is engraved
Movement number on the movement; case number on the caseback.

How to read a result

A window is the span of years in which the number’s block was issued. Boundaries can shift by a year or two, so a window covers every year the number could belong to rather than a single guess.

The result dates the numbered component: a movement may have been cased and sold later, and a case can carry a replacement movement. A number that fits a window does not authenticate a watch; genuine serials have been copied onto counterfeits. For a recorded date, request the manufacturer’s archive extract. 4 brands are listed as not covered because their numbers cannot be dated reliably.