Just an average girl: Charlotte Church, size 14
Traditional women's clothes sizes, such as 12 or 14, are to be dumped because they vary too much from retailer to retailer.
Instead, items will be labelled with exact measurements for key areas such as bust, waist and hips.
The new standard system is being drawn up by the EU, which is concerned about the ad-hoc way stores are tinkering with the current descriptions.
To appeal to the ego of shoppers, retailers have been adding extra inches of material without changing the labels.
A size 12 frock, for example, could vary by more than one inch in the bust depending on the designer.
While it has proved to be a huge money-spinner for the stores, this "vanity sizing" will soon come to an end.
The European Committee for Standarisation is working on the new regime. Effectively, it will require fashion designers and retailers to put measurements on the label.
Committee chairman Frank Moore said: "It could be the end of the size ten. It will take some time but will mean better sizing for consumers."
The system will start on the Continent first, and then come to Britain. H&M, which has stores in 28 countries, has already begun using body size labels in some countries.
The system that most others are using starts at four - a U.S. size zero - and runs up to 30 and beyond.
But a survey by Which? magazine found that these descriptions are becoming meaningless.
At Dorothy Perkins, a size 14 - such as Charlotte Church would have worn pre-pregnancy - has a bust measurement of 38.2in, one and half inches more than at Marks & Spencer, the survey found. Similarly the waist on a size 14 at Dorothy Perkins measures 30.7in, which is almost an inch of extra give compared to M&S.
A look at hip measurements on size 14 shows a similar picture. The figure is put at 40in at Dorothy Perkins, which is around half an inch more than clothes from M&S and Next. Hips for Tesco fashions come in even bigger at 40.6in.
Scroll down for more...
Psychologist and expert in consumer behaviour, Dr Joan Harvey, of the University of Newcastle, said vanity sizing is a very powerful ploy.
"Anything that makes people feel thinner is a clever move," she said.
"Women who would normally be regarded as a 14 or 12 are delighted to find they can fit into something smaller. They are likely to keep coming back." Others, however, find the lack of consistency confusing. One shopper questioned by Which? in Oxford Street, Carla Bousfield, said: "It's annoying there isn't a standard, so that a size 14 fits in every store.
"Trying on clothes isn't always an option so just grabbing a T-shirt can lead to problems.
"They manage to stick to sizing when it comes to televisions, as a 21in screen is a 21in wherever you buy it. Beds are the same - a king is a king - so why can't we buy a size 14 that is a size 14?"
The stores involved argue the changes to their standard sizes are necessary to reflect the changing shape of the population. Women are becoming taller, broader and wider, largely because of better food and less active lifestyles.
The National Sizing Survey, published two years ago, found a remarkable change in body shapes over the last 50 years.
The average waist for a woman went up from 27.5in to 34in, the hips were 1.5in wider at 39in and the bust increased by the same amount to 38.5in. Women were also 1.5in taller at an average of 5ft 4.5in. A similar pattern was seen with men.
SEAN POULTER, For The Daily femail
