Originally Posted by Sarn

Comparisons using PPP are arguably more useful than nominal when assessing a nation's domestic market because PPP takes into account the relative cost of local goods, services and inflation rates of the country, rather than using international market exchange rates which may distort the real differences in per capita income.[2] It is however limited when measuring financial flows between countries.[3] PPP is often used to gauge global poverty thresholds and is used by the United Nations in constructing the human development index.[2] These surveys such as the International Comparison Program include both tradable and non-tradable goods in an attempt to estimate a representative basket of all goods.[2]

https://en.wikipedia.org/wiki/List_o...s_by_GDP_(PPP)

1 People's Republic of China 20,853,331
? European Union[n 1] 19,205,364
2 United States 18,558,129
3 India 8,642,758
4 Japan 4,901,102
5 Germany 3,934,664
6 Russia 3,684,643
7 Brazil 3,101,247
8 Indonesia 3,010,746
9 United Kingdom 2,756,748
10 France 2,703,378
11 Mexico 2,227,176
12 Italy 2,170,909
13 South Korea 1,848,518