Dayton is about 4.2 times smaller than Madrid.

Madrid is approximately 604 sq km, while Dayton is approximately 145 sq km, making Dayton 23.92% the size of Madrid.
Tip: This to-scale comparison of Madrid vs. Dayton 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.