Isle of Man is about 3.2 times bigger than District of Columbia.

District of Columbia is approximately 177 sq km, while Isle of Man is approximately 572 sq km, making Isle of Man 223% larger than District of Columbia. Meanwhile, the population of District of Columbia is ~601,723 people (510,341 fewer people live in Isle of Man).
Tip: This to-scale comparison of District of Columbia vs. Isle of Man uses the Mercator projection, which distorts the size of regions near the poles.