Clothes with the same size label have become steadily larger over time. Measurements vary a bit by brand, but research by The Economist finds that the average British size-14 pair of women’s trousers is today more than four inches wider at the waist than a size 14 in the 1970s, and over three inches wider at the hips.
This means that today's size 14 fits like a former size 18; a size 10 fits like an old size 14. The same "downsizing" has also happened in America where, to confuse matters further, a size 10 is equivalent to a British size 12 or 14, depending on the brand.
As the average person’s weight has risen over the years, fashion firms have increased the measurements of their garments, partly in the belief that women feel better (and so are more likely to buy) if they can squeeze into their old size.
24 April 2012
"Size inflation" in clothing