Spain is to standardise its clothing sizes for women as part of a government drive to ease pressure on young girls over their body size.
Mannequins are likely to be made in more realistic sizes
Clothes currently on sale in Spain often vary in size from shop to shop, despite carrying the same size label.
Some fear the labels are confusing shoppers and that efforts to conform could be leading to eating disorders.
The move follows Spain's ban of ultra-thin models on the catwalk during Madrid fashion week last September.
Spanish women often head into changing rooms with an armful of different sizes never knowing which one will fit this time or whether any will fit at all.
But by 2008 those days could be over. Spain's biggest fashion retailers have bowed to government pressure to standardise their sizes and reflect the real size of Spain's growing population.
Under new regulations, a size 40 garment in one store will need to be at least roughly comparable to a size 40 in another shop.
Survey of sizes
There will also be a push to increase the sizes of shop window mannequins to at least a European size 38.
Spain's health ministry described the current ones as unreal dolls of "alien dimensions", which it sees as directly encouraging eating disorders such as anorexia.
Spanish authorities want to ensure beauty is linked to health
"It is not reasonable for a modern and advanced society to establish stereotypes of beauty that are far removed from the social reality of a community," said Health Minister Elena Salgado.
"It is everyone's commitment that beauty and health go hand in hand."
The move is likely to affect women and girls all over the world as international brands such as Mango and Zara have signed up to the agreement.
The change of sizes will be led by Spain's National Consumer Institute, which will measure more than 8,000 Spanish females between the ages of 12 and 70.
Spanish fashion houses will then try to fit clothes to them, rather than the other way round.
Last year Spain's main fashion show banned designers from using so-called "size zero" women to model their collections.
Now designers aiming for commercial markets should be encouraged to "promote a healthy physical image that conforms with the reality of the Spanish population," the ministry said in a statement.