Sao Paulo is about 3.7 times bigger than Athens.

Athens (map shows its 34 named neighbourhoods; the area covers the whole city) is approximately 412 sq km, while Sao Paulo is approximately 1,523 sq km, making Sao Paulo 270% larger than Athens.
Tip: This to-scale comparison of Athens vs. Sao Paulo uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.