The pocket watch sizes below refer to the movement size. These measurements are not related to the size of the case or dial. This chart will convert American pocket watch sizes to millimeters.

Shop the KeepTheTime collection of antique pocket watches here!

Size Inches Millimeters
20s 1 5/6 46.56
18s Common 1 23/30 44.86
17s 1 22/30 44.02
16s Common 1 21/30 43.18
14s Common 1 19/30 41.48
12s Common 1 17/30 39.78
10s Common 1 15/30 38.10
8s Common 1 13/30 36.40
6s Common 1 11/30 34.70
0s Common 1 5/30 29.62
3/0s Common 1 3/30 27.94


9 Responses

  1. Michelle

    Thanks for sharing this chart. It will be very helpful when shopping for junk watches for use in Steampunk jewelry and art.

    • Watch in my pocket

      If you’re shopping for broken antique pocket watches for jewelry then why would you need to know the size? Just curious.

  2. Phil

    Hi, I am confused. All the data I have researched including the table here informs me that according to the serial number, the Elgin 7 jewel pocket watch I have is a 1927 16s, yet when I measure the actual movement it has a size of 40.6 mm indicates it is a 13s size. Can someone please clarify what’d size the movement is that I have. Cheers. Phil

  3. Bob Watch Guy

    Thank you, Thank you, Thank you. This came in really handy in figuring out the size of my grandfathers pocket watch.

  4. Watch in my pocket

    Does anyone know what the S means on pocket watch sizes?


Leave a Reply

Your email address will not be published.