We got two sets of these for our trip to Europe where we were taking carry-on only. In November, we needed lots of warm, thick clothes, so every inch of space counted. These bags were amazing. I fit almost all my clothes into the large one (other than the clothes I wore): one pair of pants, one sweater, two t-shirts, one long-sleeve tee, a pajama shirt, and a pair of leggings. The small one fit all my underwear and socks plus another pair of leggings. They fit easily into our Osprey Farpoint (40L) packs. Won't ever travel again without them!