I've had several pairs of Birk sandals over the years and these fit basically the same, which is to say, very well. Personally, my size is between a US 9.5 and 10, so the size 43 is a bit large, but better than a bit small. That I'll be wearing these clogs with socks makes that no real issue. As with any Birkenstock product, there's a break in period to be endured, but well with the effort.