HAVAIANAS run bigger than US sizes. This is a general sizing guide and sizing may vary.

Brazil 35/36=US 4/5 Fits US size 5 to 6
Brazil 37/38=US 6 Fits US size 6 1/2 to 71/2
Brazil 39/40=US 7/8 Fits US size 8 to 9
Brazil 41/42=US 9 Fits US size 9 1/2 to 10 1/2