I just tried out the calculation, and can't get it to work. It says I should be wearing a size 20 or thereabouts now, whereas I am in a UK 16 (US 14??)
What am I doing wrong? I think you take the 11.11 away at the end, rather than add it, but even so it seems wrong.

Any hints? It is such a clever idea, to factor in height weight and age, I would love to use it properly.