Brazil size 35/36 fits US Women's size 4/5, Brazil size 37/38 fits US Women's size 6/7, Brazil size 39/40 fits US Women's 8/9, Brazil size 41/42 fits US Women's 10/11.

Product Description
Carefree style and these lively thongs from Havaianas go together like two peas in a pod. Molded rubber upper in a casual flip flop three point thong sandal style with a rounded toe post, molded pattern and Havaianas logo detail. Smooth interior, cushioned soft rubber geometric printed footbed. Flexible, cushioning foam midsole. Traction patterned outsole. Sizes S (fits 4 -5 US, 35-36 Euro), M (fits 6-7 US, 37-38 Euro), L (fits 8-9 US, 39-40 Euro), and XL (fits 10-11 US, 41-42 Euro)

Amazon.com Product Description
Made in Brazil of the finest, softest rubber, the Pois from Havaianas is an ultra-comfortable flip-flop that's perfect for poolside or building sand castles on the beach. This light and easy thong has a shimmery molded rubber upper with a Havaianas logo, a geometric circle patterned insole, a shock absorbing midsole to keep you light on your feet and a durable rubber outsole for a steady step.

Customer Reviews:

Review #1
Wrong size
I was also sent the wrong size. The sizes on the boxes are all mixed up. I had to return them.

Review #2
Nothing special
I received these flip flops today. First of all I was sent the wrong size, but these shoes are nothing special...just regular ol' flip flops!! It is definitely not like walking on marshmallows that's for sure!!!! I should've know, they are way too thin for that!!!