Additional size number

Additional size number is an extra space in a shoe - the difference between the shoe length (or width) and the foot itself. Sufficient over-dimension gives the foot room to function correctly. Extra space of about 4-5 mm should be present in every shoe for a correct unwinding of the stride. When buying new shoes for children, we recommend an additional room number of about 10-12 mm for optimal foot growth. Adults usually opt for an oversize of 5-6 mm for closed walking shoes, 7-10 mm for sports shoes, and only 2-3 mm for open-toed sandals.