Same size as the 44mm, just has larger screen real estate. (smaller bezel)I wear a series 4 44mm, so I may be ordering one and gifting the 4 to a friend that has a 1. I'm wondering if the series 7 45mm is just going to be too big on my wrist, though a bigger screen may offer some advantages by way of display. Weight in stainless, in the 45mm, is of course another factor. Maybe it is time to go aluminum?