Idaho is around the same size as Utah.

Utah is approximately 212,751 sq km, while Idaho is approximately 214,314 sq km, making Idaho 1% larger than Utah. Meanwhile, the population of Utah is ~2.8 million people (1.2 million fewer people live in Idaho).
Tip: This to-scale comparison of Utah vs. Idaho uses the Mercator projection, which distorts the size of regions near the poles.