If you are a size 5 then you will need a 6 top. I washed this i warm water and hung dry and it shrunk a bunch. I am usually a size 6 after I wash and dry my Gi's, while I know this is not the recommend way of doing things it is the most practical. Like I said i just washed this top in warm and hung dried it and it still shrunk a lot so that it hardly fits.
BTW the matching pants are great and only shrink what most of us would expect. Samurai Club Kansas ' roninkan.com