I have super wide feet and bought these upon the recommendation of my brother, who also buys this brand and has very wide feet. For reference, my feet are 4.5-5 length and 10 width  I usually have to wear size 6-7 to find anything that fits me.

I bought this in a size 35 and holy cow, it's so comfortable. I run in minimalist shoes and find it's been the best thing for my foot health. But weirdly enough...these were too big? I thought a size 5-5.5 would fit me just fine but there is a solid 1.5-2cm of gap at the end of my toes. I wear a wide size 5D in New Balance Minimuses just fine.