Love these trousers & I have the “Sage My Name” Blazer to match! I am 5’6 and I weigh 138 pounds. So I wear a US size 8 in pants so I ordered a medium and they fit me great. I would say if you’re in between sizes or prefer a looser fit go ahead and size up in the trousers.
Also if you were thinking about getting the blazer to match (which I highly recommend!) if you want the oversized look then size up! I purchased the large in the blazer and it’s the perfect oversized feel I wanted!
Don’t even hesitate go ahead and buy the set!