Shoe size
Common sizing systems
Shoe size in the United Kingdom, Ireland, India, Pakistan and South Africa is based on the length of the last used to make the shoes, measured in barleycorns (​1⁄3 inch) starting from the smallest size deemed practical, which is called size zero. It is not formally standardised. Note that the last is typically longer than the foot heel to toe length by about 1⁄2 to 2⁄3 inch (13 to 17 mm).
Shoe size-13