In my experience, (YMMV) most XL jackets will technically have the same sleeve length as an XXL within a quarter inch. However when wearing them an XXL may appear (on a smaller chested and smaller shouldered person) to have an extra inch in sleeve length. I used to wear XXL and then lost 35+ lbs. and now wear an XL. I don't think the sleeves on the XXL jackets are actually longer, but because I lost weight on my shoulders and chest the shoulder line on my older/bigger gear falls out and downward which makes the sleeves APPEAR longer than they actually are, but it is actually just loose and floppy around the shoulders that makes it that way.
To put it in perspective, I have a winter riding jacket that is XXL, and I still wear it, but I wear a thick inner jacket under it (when you loose 35 lbs. of fat you get colder easier). When I do that the sleeves are correct. But if I wear the winter riding XXL jacket without a fleece jacket and a long sleeve shirt underneath then the sleeves are 3/4 inch too long, but I think it is not that the sleeves are long it is that the shoulder pads are hanging outward and downward.
11 months ago