Manchester is about 18 times smaller than Santiago.

Santiago (area of the 32 comunas of Santiago Province) is approximately 2,030 sq km, while Manchester is approximately 116 sq km, making Manchester 5.69% the size of Santiago.
Tip: This to-scale comparison of Santiago vs. Manchester 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.