I just about live in Vibram FiveFingers or "normal" looking super minimalist shoes. Translation: my toes now want plenty of room in the toe box area. In VFFs, I wear a 39 or 40, depending on the model, and typically, with thick socks. In regular sneakers/shoes, I'm an 8-8.5, and I typically size up to 8.5. Dress shoes/pumps = 8.

With this model, after reading certain reviews, it appeared my wiser choice would be a 9, even though I've never before gone that high. Lemme tell ya -- I'm sooo glad I listened!  The 8s definitely would have been too short, with or without socks. Fresh out of the box, yes, I am conscious of the toe box area. Nonetheless, they're  close to a perfect fit. I have no doubt that as I continue to wear them, they'll loosen up a bit, at which point they will indeed be perfect.

FYI: I was wearing Injinji's Original Weight socks with my VFF KomodoSports when this box arrived. I immediately switched to the slippers, with the socks still on. When I later removed the socks, these slippers were still ultra comfy. Toasty and warm, without being suffocating. My advice: if you're shopping around for slippers, try these first. I suspect you too will fall in love. If you're shopping for someone else, peek inside 2 of her shoes. Whatever the size, go up one. Much more likely to yield the proper fit.