# Deciphering the Grand Seiko Numbering System



## riddlers (Sep 24, 2013)

I am sure there are trick to deciphering the Grand Seiko numbering system or even the Seiko system in general. Any of you learned folks care to share you knowledge? Thank you.


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## Nokie (Jul 4, 2011)

Here is a start-

https://www.watchuseek.com/f21/grand-seiko-2015-all-model-numbers-1692266.html


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## Tseg (Mar 29, 2014)

This is as good as any description decoding the serial number, in case you are interested._

Seikos have the date of manufacture written into the serial number which is engraved on the back of the watch also the movement-model numbers are also engraved onto the case back. The first number represents the year and the second number (or letter) represents the month (1-9 for Jan.-Sept. and O,N and D for October, November and December).For example if the serial number was 864825 and you knew the watch was made sometime in the 1970's it would indicate it to be made in June 1978. You have to know the age of the watch to the nearest decade so sometimes it can be a little bit difficult. Usually the case style or the introduction dates of the movement can help to narrow this down though.

General rule for manufacture month/year is to look at 1st digit of serial # to say what year within decade. Then look at 2nd digit/letter to tell month. For month, 1-9 are Jan thru Sep, with 'O' for Oct, 'N' for Nov, and 'D' for Dec.

For decade itself, you have to know the actual production dates of the movement itself. If you don't you could e mail Seiko customer service in (Japan) ,quoting model and serial numbers and they should be able to help,here is their e mail address __[email protected]
_
Seiko watches production dates by serial number


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## riddlers (Sep 24, 2013)

I was more looking for the model number, for instance the S means Seiko, the G means Grand, the A means automatic, S means Spring, Q means Quartz, etc. It seems as though they would devise a system. Thanks.


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## Domo (Sep 20, 2013)

So all GSes made after the modern re-launch have 4 letters then 4 numbers. All Seiko branded watches start with "S", and something tells me this stands for "Seiko" so that's the first letter out of the way.

The next letter refers to the gender of the anticipated wearer. "B" for blokes and "T" for the ladies size.

The next letter is always "G". I assume this is for "Grand" but that's a guess. The 3rd letter traditionally denotes a lineup or collection of designs in other Seiko codes.

The final letter denotes the calibre inside the watch....

A = Spring drive, date: 9R65 or 9R15.
B = Spring drive chronograph, date:, 9R84
C = Spring drive chronograph, GMT, date: 9R86, 9R96
D = Spring drive manual wind 8 days, 9R01 (upcoming)
E = Spring drive GMT, date: 9R66
F = Quartz, date: 8J56 (discontinued)
G = Quartz, date: 8N65 (discontinued)
H = Hi-beat automatic, date: 9S85, 9S85 Special
J = Hi-beat automatic, GMT, date: 9S86, 9S86 Special
L = Automatic, PR, date: 9S67 discontinued
M = Automatic, GMT, date: 9S66, (9S56 discontinued)
R = Automatic, (date, 9S65, (9S55 discontinued)), no-date 9S64, (9S54 discontinued))
S = Quartz, no-date: 9581 (discontinued)
T = Quartz, date, day: 9F83
V = Quartz, date (larger calendar): 9F82
W = Mechanical hand-wind, no-date: 9S64 (9S54 discontinued)
X = Quartz: (date, 9F62) (no-date, 9F61)


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## samanator (Mar 8, 2008)

Thanks Domo. i think when this thread runs it's course I should move it to the reference area since I'm certain this will come up more than once.


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## riddlers (Sep 24, 2013)

Thanks to all of those who helped better understand the system. It was quite educational.


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## Toshk (Aug 3, 2015)

Surely it's not B for blokes


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## Lunar Watch Club (Dec 7, 2014)

Are the numbers after the 4 letters just indicate the design?


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## appleb (Sep 30, 2015)

Toshk said:


> Surely it's not B for blokes


I was told the B stood for 'Boy'. I guess Blokes is another way to refer to a male in Australia.


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## CydeWeys (Jan 16, 2021)

There are now models where the second letter isn't a B or a T, but an L, e.g. the SLGH003. What do we make of this? I don't think it means unisex because the SLGA001 is very clearly not targeting women (it's a 47mm dive watch!). The one thing I do notice all of these have in common is that they're Seiko 60th Anniversary Limited Editions, so that must be it? It's weird because the L isn't used by their other Limited Editions, even other anniversary editions like the Kintaro Hattori 160th Anniversary SBGZ005.


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## aalin13 (Apr 2, 2010)

CydeWeys said:


> There are now models where the second letter isn't a B or a T, but an L, e.g. the SLGH003. What do we make of this? I don't think it means unisex because the SLGA001 is very clearly not targeting women (it's a 47mm dive watch!). The one thing I do notice all of these have in common is that they're Seiko 60th Anniversary Limited Editions, so that must be it? It's weird because the L isn't used by their other Limited Editions, even other anniversary editions like the Kintaro Hattori 160th Anniversary SBGZ005.


The SLGA and SLGH are used to designate the new 9RA5 and 9SA5 movements. SBGZ is for watches with the 9R02 movement. The first four letters are used to according to the movement of the watch, not whether it's a limited edition.


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