Nebraska is about 1.9 times smaller than Montana.

Montana is approximately 376,979 sq km, while Nebraska is approximately 199,099 sq km, making Nebraska 52.81% the size of Montana. Meanwhile, the population of Montana is ~989,415 people (836,926 more people live in Nebraska).
Tip: This to-scale comparison of Montana vs. Nebraska uses the Mercator projection, which distorts the size of regions near the poles.