bazinjnWhen I read your question, yea, 13mm seems like a lot so I measured some of my various watches and NO, 13mm is not a lot. A Rolex GMT master is 13mm as are several watches in this style I have with a 40mm +- diameter. I have a vintage very slim smallish Rolex men's dress watch that is 35mm diameter and it is 12.5mm. Typically the back cover is 2-3mm so that doesn't show on your wrist as thick when wearing.