In absence of a size chart I purchased a medium to be on the safe size as the dress appeared like it was made from a stretchable material. I found out the hard way the dress though it appears loose is not stretchable on the chest area at all. The medium for a larger than average chest was way too small, in fact the dress was suffocating my chest. Instead of returning the dress I ended up gifting the dress to an individual with a slightly smaller chest size. I highly recommend sizing up 1-2 sizes if you have a larger than average chest but are "skinny" elsewhere. If you are worried about the dress being too oversized on the bottom verses the top then I would belt the bottom area.