Amazon calculates a product’s star ratings using a machine learned model instead of a raw data average. The machine learned model takes into account factors including: the age of a review, helpfulness votes by customers and whether the reviews are from verified purchases.
I am usually a US size 6 and purchased this flipflop in size 7/8 but still find it too tight. Also the back of my feet is slightly outward off the flipflop. Other than size, the material is very comfortable.