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.

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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

6 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.

  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


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