Dress sizes are not consistent across the globe and a number of major clothes sizing systems are used across the world, including two in the US (Misses' sizes and Women's sizes), one in the UK and three in Europe (French, German and Italian). Other countries in Europe usually use one of the French, German or Italian systems and other North American countries the US systems.
In addition to these there is the new European clothes size standard EN13402, see below for more information.
Dress Size Conversion Chart
The US dress sizing systems are also used in Canada and many caribbean nations, UK sizes are also used in Ireland, Australia and New Zealand. In Europe it is more complicated but not too difficult to remember as the German sizing system is used in countries that speak germanic languages (Austria, Holland, Sweden and Scandinavia), the French system is used in latin speaking countries (Spain, Portugal, Luxembourg and Belgium) apart from Italy which uses its own system. There are similarly differences in shoe sizes between the US, UK and Europe (although there is a standard European shoe size system). South Africa uses the German (European) sizing system, although many outlets have conversion to UK sizing.
EN13402 New European Clothes Size Standard
EN13402 is a relatively new European clothing size standard based on body dimensions it has been designed to combat a number of issues with current sizing systems, including the issue of vanity sizing, that create significant differences in the actual measurements of garments with the current ad hoc numbering systems. It also provides measurement system which can cope with garments that need two or three dimensions in order to provide a good fit for an individual.
In 2007 the European Standards Commission launched EN13402 to standardize clothes size labels based on body dimensions in centimetres (cm). The commission had been working on the standard since 1996 and like other sensible measurement systems (e.g. Mondopoint Shoe Sizes) it hasn't been widely adopted yet.
EN13402 is divided into 3 sections, the first provides terms, definitions and the body measurement procedure. The second part defines primary and secondary measurements for various items of clothing, for instance the primary measurement for ladies jackets is bust girth and secondary measurements are height and hip girth. The third part defines measurement intervals which should be used for each of the body measurements defined in part 1.