I am a true 7 and the medium fits my foot perfectly. No blisters for me because this is my third pair of rainbows but if they are hard to break in for anyone else try wearing them in the ocean or in the shower of the first few days. That will help break them in faster. I love the look of these and they last forever!! The last pair I had lasted me 2 years and they were nowhere near their last leg!! I recommend these shoes to everyone I know.