Pocket Watch Size Information

Please do not call us for antique pocket watch information and/or values.
We do not sell, research, nor offer appraisals or values for used, vintage, or antique watches.
The information provided is for reference only.

Please see our watch information section, or visit the NAWCC Message Board if you need further assistance.

18s, 12s, 3/0…  what does this mean?  Below is a table to convert an American pocket watch size to inches and millimeters.  This measurement refers to the size of the movement, as measured at the dial plate, not the case or dial.
Finally, YES they were measured in 30th of an inch, not 32nds!

Size (Lancashire) 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

Watchmakers and hobbyists – Click here for the free downloadable version (must have Adobe Acrobat or equivalent to view the .pdf file).