Detroit is about 14 times smaller than Auckland.

Auckland is approximately 4,894 sq km, while Detroit (map shows its 92 named neighbourhoods; the area covers the whole city) is approximately 359 sq km, making Detroit 7.34% the size of Auckland.
Tip: This to-scale comparison of Auckland vs. Detroit 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.