Tanzania is about 4.4 times bigger than Idaho.

Idaho is approximately 214,314 sq km, while Tanzania is approximately 947,300 sq km, making Tanzania 342% larger than Idaho. Meanwhile, the population of Idaho is ~1.6 million people (62.3 million more people live in Tanzania).
Tip: This to-scale comparison of Idaho vs. Tanzania uses the Mercator projection, which distorts the size of regions near the poles.