Globally there are 7 major shoe size systems, with the US, British, European and Japanese size systems being the most common ones across the world.
The size conversion is useful for people who shop in US or European online stores for shoes and clothing, which are usually cheaper than in your country.
The European shoe size system is less standardized than others around the world. A French or a German shoe size can be totally different based on manufacture or brand. With that said, please use the chart as a guiding principle while knowing that sizes can and do vary by brand manufacturer and country.
International shoes size conversions: