It is just slightly loose, not tremendously so but if you aren't wearing a sock you might walk out of it, of course that depends on your own foot size and shape. I am a true 11/42 and I have a Halfinger now that is a 41 and it is big, I have tried 42's that are too tight. If you don't have Prime I'd see about whether you can get a free return if they don't fit right.

Before I bought the slipper I saw advertised - AT Storm Flat - I specifically asked other buyers whether it has the cork foot bed (as opposed to the whole sole). That foot bed will conform to the bottom of each individual foot and I just love it. I got 8 replies and many said yes, it has a cork sole.  I ordered and was very disappointed to see that with AT Storm we walk on a hard rubber sole. My only conclusion is that when I asked "the community" for help the request goes out to anyone who bought a Haflinger brand slipper regardless of style. Good thing I had Prime so the return was free.