Nevada is about 1.3 times bigger than Idaho.

Idaho is approximately 214,314 sq km, while Nevada is approximately 284,448 sq km, making Nevada 33% larger than Idaho. Meanwhile, the population of Idaho is ~1.6 million people (1.1 million more people live in Nevada).
Tip: This to-scale comparison of Idaho vs. Nevada uses the Mercator projection, which distorts the size of regions near the poles.