District of Columbia is about 43,736 times smaller than Australia.

Australia is approximately 7,741,220 sq km, while District of Columbia is approximately 177 sq km, making District of Columbia 0.0% the size of Australia. Meanwhile, the population of Australia is ~26.1 million people (25.5 million fewer people live in District of Columbia).
Tip: This to-scale comparison of Australia vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.