These are not even close to being the most comfortable shoe I've ever worn. In less than 5 steps I could feel the back of the shoes grating on my heels. By the end of the day I had 2 blisters on the heels. The tip of my toes and the top of my foot (the tarsal-metatarsal joints) were extremely sore. I wear a size 8 in everything except my running shoes where I wear an 8.5. My past 2 pair of shoes were Danskos and Sauconys... those I wore for 12 hrs right off the bat with no problems whatsoever. Thankfully Allbirds has a 30 day return policy.