According to Investopedia:
Typically, the first metric economists look at when determining development status is per capita GDP; this is the value of all goods and services produced within a country's borders, divided by its population. While most developed countries have per capita GDPs of $30,000 or above, some economists accept a value as low as $12,000 to $15,000 if a country is strong in other areas.
Developed countries almost invariably have higher life expectancies, lower infant mortality rates and higher educational attainment than developing countries. A lower proportion of citizens live in poverty, while access to quality health care and higher education is widespread, if not universal.
Reference: Investopedia (2016) Is China a developed country? . Available from < http://www.investopedia.com/ask/answers/113015/china-developed-country.asp > [22 Feb 2016]
