I wish I could find some useful population density information for St. John's.
I can find it for the entire municipality (244.8/km sq), but the city limits encompass massive, undeveloped areas. Not even park lands - just wilderness land claims extending far beyond the urban area.
However, the population density of Mount Pearl - which would certainly be less than St. John's - is 1,542.1/km sq.
So the urban area of St. John's should be somewhere in that neighbourhood but a little denser, I think.