Tanzania is about 5,352 times bigger than District of Columbia.

District of Columbia is approximately 177 sq km, while Tanzania is approximately 947,300 sq km, making Tanzania 535,098% larger than District of Columbia. Meanwhile, the population of District of Columbia is ~601,723 people (63.3 million more people live in Tanzania).
Tip: This to-scale comparison of District of Columbia vs. Tanzania uses the Mercator projection, which distorts the size of regions near the poles.