Norfolk Island is about 4.9 times smaller than District of Columbia.

District of Columbia is approximately 177 sq km, while Norfolk Island is approximately 36 sq km, making Norfolk Island 20.34% the size of District of Columbia. Meanwhile, the population of District of Columbia is ~601,723 people (599,975 fewer people live in Norfolk Island).
Tip: This to-scale comparison of District of Columbia vs. Norfolk Island uses the Mercator projection, which distorts the size of regions near the poles.