A size 4 shoe corresponds approximately to a foot length of about 4.5 inches (11.4 cm) for toddler sizes and around 23.5 cm (9.3 inches) for adult UK size 4. The exact measurement depends on whether the size is for toddlers, kids, or adults and the regional sizing system used (US, UK, EU). For instance, a toddler US size 4 is about 4.5 inches long, while a UK adult size 4 is about 23.7 cm or 9.3 inches in foot length.