District of Columbia is about 8 times bigger than Nauru.

Nauru is approximately 21 sq km, while District of Columbia is approximately 177 sq km, making District of Columbia 743% larger than Nauru. Meanwhile, the population of Nauru is ~9,811 people (591,912 more people live in District of Columbia).
Tip: This to-scale comparison of Nauru vs. District of Columbia uses the Mercator projection, which distorts the size of regions near the poles.