What does UK shoe size mean?

It's your shoe size in the United Kingdom.

Because the United States uses the older, outdated imperial system, while the United Kingdom uses the modern, updated metric system, the measurements are different.

UK and US shoe size comparisons:

UK Size 2 = US Size 4.5

UK Size 2.5 = US Size 5

UK Size 3 = US Size 5.5

UK Size 3.5 = US Size 6

UK Size 4 = US Size 6.5

UK Size 4.5 = US Size 7

UK Size 5 = US Size 7.5

UK Size 5.5 = US Size 8

UK Size 6 = US Size 8.5

UK Size 6.5 = US Size 9

UK Size 7 = US Size 9.5

UK Size 7.5 = US Size 10

UK Size 8 = US Size 10.5