Utah is around the same size as Idaho.

Idaho is approximately 214,314 sq km, while Utah is approximately 212,751 sq km, making Utah 99.27% the size of Idaho. Meanwhile, the population of Idaho is ~1.6 million people (1.2 million more people live in Utah).
Tip: This to-scale comparison of Idaho vs. Utah uses the Mercator projection, which distorts the size of regions near the poles.