Watch Tools
Watch Tools
Free checkers to help you date a Seiko or Citizen from the serial on the caseback. More tools will be added here over time.
Enter the serial from the caseback to find the month, possible production years and the watch's age.
Date a Citizen from its serial number, then narrow the year with the calibre or decade if you know it.
Wrist size, strap finder and a simple age calculator will appear here. This page is built so new tools are easy to add.
Seiko serial date checker
Enter the serial number from the caseback to find the production month, the possible years and the watch's approximate age.
The serial only gives the last digit of the year, so a 6 could be 1976, 1986, 1996 and so on. Adding the calibre or a decade makes the result much more accurate. This is a guide, not an official Seiko dating service. Watches from before about 1967 used 7-digit serials, and a few of those put the month first, so treat very early results with care. Seiko 5 Sports models from 2019 onwards (with the newer “5” logo) use a different serial that cannot be dated this way. Production years for each calibre are approximate collector figures.
Citizen serial date checker
Enter the serial number from the caseback to find the production month, the possible years and the watch's approximate age.
The serial only gives the last digit of the year, so an 8 could be 1978, 1988, 1998 and so on. Adding the calibre or a decade helps, though long-running movements such as the 8200 often still leave more than one possibility. Citizen used more than one serial format, and a few watches have month digits that cannot be read (such as 00). This is a guide, not an official Citizen dating service. The serial usually dates the case, which may not be the same month the finished watch was completed.