Seiko Serial Numbers Complete Guide and Date

Seiko Serial Numbers Complete Guide and Date

What is the serial number on a Seiko? Where is the serial number on a Seiko, and how can you use it to date your watch? These are common questions that we get from our readers.

To help you identify the year of your Seiko, and to understand when it was made, we have compiled a complete Guide to Seiko watch serial numbers. Dig in!

Background to Seiko serial numbers

The vast majority of timepieces feature a serial number. This is especially true for luxury watches and mechanical watches that are made not only as a means of telling the time but also to appreciate.

With that said, all Seiko watches are equipped with serial numbers.

The serial number has a number of different purposes. Most important, it helps the manufacturer keep track of each and every single watch they produce. But at the same time, the recorded databases of the serial numbers are rarely shared with the public but are used and kept by the company alone. This also includes Seiko.

Seiko watches are equipped with several different numbers.

Seiko case back number

The numbers on a Seiko can be found on the case back. There, you will find a number that actually refers to two different numbers – the case code and the caliber (movement).

The number on the Seiko case back consists of one number, a hyphen, and then an additional number. Both of these consist of four digits. These do not make up the serial number.

The serial number contains six digits and can also be found on the case back. Each Seiko watch has a serial number that is unique to that exact watch.

Furthermore, the case back of a Seiko watch reveals a bunch of different information. This includes the date of manufacturing, the movement type, case material, the maker, how to open the caseback, and more. In some cases, part of, or all, this information, is indicated on the inside of the case back, which means you need to open it in order to access it.

Note: This article is for informational purposes only. To the best of our knowledge, it is correct, but typos or mistakes may exist.

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How to date your Seiko watch with the serial number

The good thing is that you can use the serial number of your Seiko to date it in order to know when it was produced.

The format for dating it via the serial number is as follows:

The first digit in the number will indicate the last digit of the year the watch was manufactured. The second digit indicates the month, and the last 4 digits are the production number, which is unique to the watch.

Seiko started with the six-digit serial numbers in 1966, which means you will not be able to use the below methods to date your watch. Prior to this, Seiko used seven digits. Note that during this time, there was a transition period where both systems were used.

This means that when the first digit indicates:

  • 1: The year of manufacture ends with 1
  • 2: The year of manufacture ends with 2
  • 3: The year of manufacture ends with 3
  • 4: The year of manufacture ends with 4
  • 5: The year of manufacture ends with 5
  • 6: The year of manufacture ends with 6
  • 7: The year of manufacture ends with 7
  • 8: The year of manufacture ends with 8
  • 9: The year of manufacture ends with 9

Worth noting is that the month (second digit) is indicated as 1-9 for January to September. 0 is October, N is November, and D is December. As seen below:

  • 1: January
  • 2: February
  • 3: March
  • 4: April
  • 5: May
  • 6: June
  • 7: July
  • 8: August
  • 9: September
  • 0: October
  • N: November
  • D: December

With that said, this information does not tell us the decade in which the watch was manufactured. This is a bit trickier but possible. In order to know when your watch was made, you need to know in which period the watch was released. The way you can do this is to research the model but also the caliber number. This is helpful as most Seiko calibers (movements) are not in production for more than a decade. Those often have small visual differences that allow you to know if it is an early movement or a late movement.

It also helps to research the model itself to know when it was released and when it was discontinued.

The last four digits of the Seiko serial number tend to be a bit more tricky to read. Generally, the last four digits indicate the production number of the watch. For example, 5000 indicates that it is the 5000th watch from that model. There are exceptions to this rule, however.

Lastly, there are also helpful Seiko serial number decoders online that you can use. To decode your Seiko with these tools, you need to do is enter your serial number and movement number.

How to find the year of your Seiko watch

108 thoughts on “Seiko Serial Numbers Complete Guide and Date

  1. Hi, any idea what does number 111 mean — it’s placed at the inside of the titanium/steel straps of SARX033 or SARX035 model (top of the strap on both sides, close to the case)?
    Thank you for explanation, best regards.

    1. Hi,
      It sounds like you are talking about the end links on the bracelets. Some end links are marked to indicate which type of end links are used.

      Kind regards,
      Millenary Watches

  2. I need to know the Year that my watch was made.

    Please email me

  3. How much should I expect to pay for a full service on a Seiko 5 from 1969? I am certain that the movement is in good condition, but the day/date has stopped working. It is my father’s watch and I am willing to pay to get it back to full working condition.

    1. Hi,
      It depends on the condition of the movement and whether or not any parts need to be exchanged and who does it but generally, for standard movements, you can expect a service cost of $300 to $500.

      Kind regards,
      Millenary Watches

  4. Hi, I had a Seiko watch for my 18th birthday in 1985, it’s serial number is 340118, it’s not been working for a while but would like it repaired, could you please give me an estimate of it’s value to decide if it’s worth the repair costs.

    1. Hi,
      Since the serial number is unique to each watch, we would need the reference number/model number and photos of the watch.
      You can request assistance here:

      Kind regards,
      Millenary Watches

  5. I have a Seiko Quartz with Calendar, Ref on the back( model No?) 5Y23-7050 Set No: 019839…any info would be great handed down to me from Father in Law

  6. My Seiko Serial #972222 Movement # 7132 and Case Code-6L90 Water Resistant 20 BAR Battery Replaced and now Second Hand operates. Time hands do not. Would the
    battery replacement cause this, or did they replace the battery with wrong type, or what would be the reason for the failure. Your help is appreciated. I have had my Seiko
    for 26 years and only had the battery replaced as needed.

    1. Hi,
      It’s difficult to say without having inspected it but I wouldn’t necessarily say that it is due to the use of the wrong type of battery. It could be but it sounds like it is more likely that it is something else, for example, something that needs to be adjusted in the mechanism in itself. Our best advice would be to take it to a watchmaker who will be able to inspect and troubleshoot it and find what is causing the issue.

      Kind regards,
      Millenary Watches

  7. Hi I have a SEIKO Titanum watch the only numbers I can see are..352775…v762-0880 any ideas as to when it was made?

  8. 702876 serial number then there is 7019 8180 no idea

    1. Hi,
      None of the numbers you provided are commonly used by fake Hublot watches. With that said, we always recommend having it checked by a professional watchmaker in order to say for certain.

      Kind regards,
      Millenary Watches

  9. I have a SEIKO watch. I am not sure of the year and its value

  10. I found a Seiko watch that appears to be in excellent shape with very few minor scratches. It weighs 166 grams, has a stainless steel wrist band and a clear back with the serial number 102126. The movement caliber is 4R36, the case code is 00S0, it has 24 jewels and is water resistant. The face has a movable dial that has the numbers 15, 30, 45 and 60 on it and it is red from 0 to about 20. I have found no info on the purpose of the red section. What is this for?

    1. Hi,
      It sounds like you have a chronograph watch, could that be the case? Chronographs are similar to stopwatches and are used to time different events.

      Kind regards,
      Millenary Watches

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