5 but bought a 5 again the length is fine but feel loose because my feet is slim and straps are not adjustable. So much better constructed than the behind the door shoe racks! My new favorite pajamas! It works nicely on a loofa or even as bubble bath. Referencing the size chart didnt really work out for me personally. Had a minor issue with one of the tips I received, and the seller sent out a replacement without any hesitation. Its large, in a good flowy way. I also love that they are easy to clean and dry. I did not measure tight as normally you want to leave some room. I rarely bother, but this was just so far off the picture and color to be acceptable.