The current population of Shanghai is estimated to be about 23.9 million people.
Contrast this with the population of the Scandinavian countries, including Norway (5.0), Sweden (9.6), Finland (5.4) and Denmark (5.6), making a total of 25.6 million.
This means that the city of Shanghai has about as many people as all of Scandinavia combined.
Including Finland among Scandinavian countries, is doubtful for both geographic and linguistic reasons. But for the numbers, it really puts things into perspective. Alternatively you could take the BeNeLux countries (Belgium, Netherlands and Luxemburg), with their total population of 28 million.
I knew some Finish people and they thought of themselves as Scandinavian. Using the Benelux is not as powerful a comparison, since those countries are densely populated and geographically small themselves.