Atlanta is about 2.4 times bigger than Pittsburgh.

Pittsburgh is approximately 143 sq km, while Atlanta (map shows its 114 named neighbourhoods; the area covers the whole city) is approximately 350 sq km, making Atlanta 144% larger than Pittsburgh.
Tip: This to-scale comparison of Pittsburgh vs. Atlanta 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.