My daughter's foot is 6 1/2 inches or 17 cm and she wears size 10 street shoes. Based on reviews I ordered her slippers 1 size up and received her size 11C and they fit perfectly! She has a narrow foot, but the "C" fits her perfectly and she still has room to grow. Very well made shoes and they should keep them.
Breathable Fashion Sneakers for Baby & Toddler Boys & Girls: Bless Children Walking & Running Shoes
54 Review
Saucony Girls Cohesion Running Little
52 Review
JambuKD Girls Outdoor Toddler Purple Girls' Shoes for Athletic
52 Review
LEOCI Soccer Shoe Coomfortable Numeric_11_Point_5 Girls' Shoes and Athletic
69 Review
DREAM PAIRS Little Aurora 03 Communion Shoes and Flats for Girls - Top Choice for Stunning Style and Comfort
49 Review
Felix Flora Toddler Flower Dress Shoes - Adorable and Comfy Flats
47 Review
Stylish and Comfortable pediped Flex Estella Mary Jane Shoes for Toddlers and Little Kids
60 Review
Adorable Blowfish Malibu Play-t for Toddler and Little Girls
47 Review