Philadelphia is about 4.3 times smaller than Mexico City.

Mexico City is approximately 1,485 sq km, while Philadelphia is approximately 348 sq km, making Philadelphia 23.43% the size of Mexico City.
Tip: This to-scale comparison of Mexico City vs. Philadelphia 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.