Apr 18,  · It's a size 6 in the UK and I believe you guys use similar sizes to us. Size 0 measurements: (according to Hollister). I think the confusion comes from the fact that a US size 0 used to be smaller in the 90's, but due to vanity sizing size 0 became a size 00 and size 2 became a size fluctuatin.gq: Resolved.