The Seiko serial number decoder
Find the manufacture date of any Seiko watch
Seiko watches have a 6 or 7 character serial number on their casebacks. The second character can be a letter but the rest are all numbers. You can use the Seiko serial number to calculate the year of manufacture. The watch's date of manufacture is calculated using the serial number and a list of Seiko movement manufacture dates. You will be given an eBay link to check the value, useful links such as manuals, etc and for quartz models the battery information.
If more than one date is returned then either I lack data for that Seiko movement or it was made for over a decade. This tool cannot be used to guarantee a Seiko's authenticity but it can be used to help spot a fake Seiko. For details of my Seiko movements list click here. For information about how this actually decodes and how to decode a Seiko serial yourself click here (also has a video showing how to find your serial number and movement).
To get the best chance of getting only one date returned it is best to enter your Seiko movement in the 2nd box. The boxes are not case sensitive. The movement can contain the letter S, which can look very similar to a 5.
My related tools Citizen, Casio, Omega, Tissot, Rolex, Breitling, Longines.