Barcelona is about 13 times smaller than Rome.

Rome is approximately 1,287 sq km, while Barcelona is approximately 101 sq km, making Barcelona 7.87% the size of Rome.
Tip: This to-scale comparison of Rome vs. Barcelona 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.