Omega f300 Case Numbers and Dates

Omega f300 Case Numbers

The Omega case number, which is stamped on the inside of the case back, is the key to helping you identify your watch.  It will allow you, or your watch repairer, to do the following:

  • Check against Omega’s Vintage Database for original brochure numbers, movement calibre, strap and bracelet options, case finishes, dial styles etc.  Unfortunately, the database is incomplete, so if your watch is not listed, don’t worry!
  • Order the correct genuine case parts for your watch. i.e. crystals, seals, crowns, pushers, bezels etc.  Over the years, generic parts are often fitted to watches — using the Omega Case Number is the best way to determine the correct Omega parts for your case.

Of course, the flaw in this is that sometimes the original case back gets lost and is replaced with another….or a watch repairer got your watch case back muddled up with another customers and swopped them by mistake.  But let’s be positive and assume the case back is original to the watch…

Meaning of the Case Number

The case number usually takes the form “nnn.nnnn” — where “n” is a digit, so an example might be “198.0002”.  It is not always four digits after the decimal place; sometime there are only three digits.  But if it is “198.0002” or “198.002” (for example), it is effectively the same case number. The first three digits tell you quite a lot about the watch and follow the codes in the table below:

1st Digit 2nd Digit 3rd Digit
1 – Gent’s Watch 1 – Manual winding without second 1 – Non-water-resistant
2 – Gent’s Jewellery Watch 2 – Manual winding small second 2 – Non-water-resistant Calender
3 – Gent’s Bracelet Watch 3 – Manual winding centre second 3 – Non-water-resistant chronometer
4 – Gent’s Jewellery Bracelet Watch 4 – Manual winding chronograph 4 – Non-water-resistant chronometer calender
5 – Lady’s Watch 5 – Self-winding without second 5 – Water-resistant
6 – Lady’s Jewellery Watch 6 – Self-winding centre second 6 – Water-resistant Calender
7 – Lady’s Bracelet Watch 7 – Self-winding chronograph 7 – Water-resistant chronometer
8 – Lady’s Jewellery Bracelet Watch 8 – Electronic chronograph 8 – Water-resistant chronometer calender
9 – Electronic
Omega f300 Seamaster Cone (198.0008) New Old Stock

Omega f300 Seamaster Cone (198.0008) New Old Stock

In the case of the Omega f300 range, with the exception of the f300 Speedsonics, the first three digits are always “198”:

  • 1: they are Gent’s watches,
  • 9: they have an electronic calibre
  • 8: they are a water resistant chronometer, with a calendar function

The f300 Speedsonics have the code “188”, reflecting that the calibre is not just a plain electronic calibre but an electronic chronograph.

Omega’s Dressing Components Catalogue

Omega Dressing Components Catalogue August 1989

Omega Dressing Components Catalogue August 1989

The second part of the case number (after the decimal place), doesn’t impart any information but is more of a sequential number that Omega used to identify each model.  One of the most useful publications to decipher Omega Case Numbers is the “Omega Dressings Component Catalogue”.  It is not easy to find a copy but from this catalogue you can perform all sorts of cross-referencing: cases-to-crystals, crowns-to-cases, cases-to-calibres and many other permutations.  I own an August 1989 Edition, and sadly, the first “198” entry in this edition is “198.0038” and the last is “198.0150”.  A quick scan of the calibers linked to those models between 198.0038 and 198.0150 shows calibres: 1220, 1230, 1250, 1260, 1511, 1516, 1346, 1343 etc, so it is important to realize that “198” not only covers the Omega f300 tuning fork models (Cal. 1250, 1260), but also the Omega Megasonic range (Cal. 1220, 1230) as well as some early quartz models.  I’m not sure why the August 1989 Edition only starts at 198.0038 but I can say with certainty that the “198” sequence starts at 198.0001 and that this is an Omega f300 Seamaster with cal. 1250 movement — I know this because I own one and it is shown in the gallery below!  Another scan of the catalogue reveals that the highest f300-related case number is 198.0076 which was a day & date model with a cal. 1260 movement.  There are no photographs or diagrams in these Omega Dressing Calatogues but a lookup of 198.0076 on the Omega Vintage Database confirms it to be Constellation model from 1976/1977 which is also when production of these ESA-produced tuning fork movements came to an end, so 198.0076 is likely to be the last Omega f300 model produced.

In conclusion, the f300 and Megasonic case numbers seem to fall into the following ranges:

  • 188.0001 and 188.0002 : f300 Speedsonic chronographs wrist watches
  • 198.0001 through to 198.0076 : f300 and Megasonic wrist watches
  • 198.1742 and 198.1742.169 : f300 and Megasonic pocket watches

A couple of pages from the Dressing Catalogue are shown below:

One final deduction from looking through the Dressing Catalogue is that the same case was often used for similar f300 and Megasonic models and this is reflected in the extra digits added to the f300 case number. I haven’t checked, but the assumption is that you ought to be able to use a date-only f300 movement in a date-only Megasonic case and visa versa…and the same with day/date movements and cases.  Some examples of these paired case numbers are:

  • 198.0038 : Megasonic cal 1220
  • 198.0038.169 : f300 cal 1250


  • 198.0064 : Megasonic cal 1230
  • 198.0064.170 : f300 cal 1260

The “.169” seems to signify “day only” while “.170” is for the deeper day & date cases.

Gallery by Case Number

The gallery below is very much a work in progress and if you can help me with missing photographs, I would be most grateful — please get in touch via the Contact page.   The information for cases 198.0001 to 198.0037 has been gleaned from Internet searches etc and should not be taken as accurate; Information for cases 198.0038 to 198.0076 has come from the Omega Dressings Catalogue mention above, so ought to be accurate but there are clearly some omissions.  For instance, 198.0047 (Megasonic) and 198.0048 (Megasonic) are fairly common cases but are not listed in my Dressing Catalogue but their f300 equivalents (198.0047.169 and 198.0048.170) are.  Therefore, I’m not responsible for any errors that may exist, so please use this information with caution.

Since starting this table, I’ve serviced a couple of customer’s f300 watches that do not fit neatly into this naming convention and are not mentioned in the Dressing Catalogue above:

  • 198.0075.004 : no idea what the “004” extension means and, to date, has not been seen on any other f300. The case appears to be solid gold although the case back is stainless steel.
  • 198.5001 : a very high sequence number and must indicate a special model for some reason.  The case and bracelet are solid 9K Gold.  More photos of this watch can be found here.

The case material key is:

  • ST : Steel
  • MD : Plated 20 micron yellow gold, steel back
  • ND : Plated 20 micron yellow gold on steel
  • CD : Cap yellow gold, 14K


Omega f300 Production Dates

The only way to date Omega f300 watches is from the serial number stamped on a plate on the movement, so if the watch has had a replacement movement, the new serial number will likely be for an incorrect year….unless the plate was moved from the old movement to the new movement.

The complete list of Omega Serial Numbers and their year is posted on the late Chuck Maddox’s website but I’ve reproduced (below) the data for the 1970s, when all Omega f300 were produced,  and I hope that is acceptable to the owners of this information:

  • 1970: 29,000,000
  • 1970: 32,000,000
  • 1971: 33,000,000
  • 1972: 34,000,000
  • 1973: 36,000,000
  • 1975: 38,000,000
  • 1976: 39,000,000
  • 1977: 40,000,000
  • 1978: 41,000,000
  • 1979: 42,000,000