Earlier, I wrote about finding which Apple Watch watchband will fit your wrist. But you may also want to try out the size of the cases.
Apple’s Apple Store app lets you see the actual size of the cases, so you can see how big they are. But holding your iPhone to your wrist isn’t helpful.
I’ve created a PDF from screenshots of the actual size Apple Watch cases in the Apple Store app, scaled so, when you print it, the images are the correct size. It’s two pages, one with the 38mm watch, the other with the 42mm watch. Print them out, cut them if you want, and you’ll see exactly how big the cases are.
I’ve left them on full pages so you can, if you wish, cut a strip of paper, above and below the image of the case, and approximate the length of a watchband.
Download the PDF with the Apple Watch case images. Make sure to print it at 100%.