Kansas City is about 6 times smaller than Auckland.

Auckland is approximately 4,894 sq km, while Kansas City (map shows its 145 named neighbourhoods; the area covers the whole city) is approximately 815 sq km, making Kansas City 16.64% the size of Auckland.
Tip: This to-scale comparison of Auckland vs. Kansas City 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.