are shoes sizes measured in inches?
The barleycorn is an old English unit that equates to 1⁄3 inch (8.47 mm). This is the basis for current UK and North American shoe sizes, with the largest shoe size taken as twelve inches (a size 12) i.e. 30.5 cm, and then counting backwards in barleycorn units, so a size 11 is 11.67 inches or 29.6 cm.