Love the shoe, but needed and bought the narrow.  I have some 37s and soe 38s at home.  It seems very slightly longer than other Birkies in that size, but admittedly, it could be my insanely narrow foot.  If you are between a 37 and 38 and need the narrow, I'd go with the 37 in styles that have only the top strap.  I am making these work, but will have to punch another hole into the strap.  It's an attractive sandal.