I think Chanel runs true to size but their shoes are narrow. I am a 6 and wear 36 in Chanel. I do have narrow feet but my problem is my calves are too big. (my excuse is that I am 5'6" and most size 36 people are tiny 5ft with tiny calves!) So only with knee-high boots, I do go up a full size to 37. So it really depends on your feet and calves.