Jacksonville is about 3.7 times bigger than Warsaw.

Warsaw is approximately 517 sq km, while Jacksonville (map shows its 197 named neighbourhoods; the area covers the whole city) is approximately 1,935 sq km, making Jacksonville 274% larger than Warsaw.
Tip: This to-scale comparison of Warsaw vs. Jacksonville 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.