18W is in Women's sizes, (fuller cut) and 18 is in misses' size (slimmer cut).
It is a 18. You have your answer in your question.
I think that it goes up in twos: 22" waist = Size 8 24" waist = Size 10 26" waist = Size 12 28" waist = Size 14 30" waist = Size 16 32" waist = Size 18 34" waist = Size 20 In my experience the UK shops vary greatly so I wouldn't rely on it. hope this helps
According to the size conversion chart a boys regular size 18 is a 29" waist and a 32" length and a husky size 18 is a 31" waist and a 32" length.
48 inches around the waist
For females about a size 16 or 18
18(w - 1)
18 inches
38
Your size is usually a 16/18.
In the UK a size 10 dress or skirt has a 28 inch waist and sizes go up in increments of 2". Size 12 would therefore have a 30" waist, size 14, a 32" inch waist, size 16, a 34" waist, size 18, a 36" waist and so on. For a waist 33" you would either have to settle for a size 14, with a 32 inch waist, or go one larger and get a size 16, which would have a 34" waist.
The waist measurement of a size eighteen dress is ninety-three centimeters or 36.5 inches. The bust size of a size 18 dress is 109 centimeters or forty-three inches.