Montana is about 1.8 times bigger than Utah.

Utah is approximately 212,751 sq km, while Montana is approximately 376,979 sq km, making Montana 77% larger than Utah. Meanwhile, the population of Utah is ~2.8 million people (1.8 million fewer people live in Montana).
Tip: This to-scale comparison of Utah vs. Montana uses the Mercator projection, which distorts the size of regions near the poles.