Montana is about 1.5 times smaller than Kenya.

Kenya is approximately 580,367 sq km, while Montana is approximately 376,979 sq km, making Montana 64.96% the size of Kenya. Meanwhile, the population of Kenya is ~55.9 million people (54.9 million fewer people live in Montana).
Tip: This to-scale comparison of Kenya vs. Montana uses the Mercator projection, which distorts the size of regions near the poles.