Mongolia is around the same size as Alaska.

Alaska is approximately 1,481,348 sq km, while Mongolia is approximately 1,564,116 sq km, making Mongolia 6% larger than Alaska. Meanwhile, the population of Alaska is ~710,231 people (2.5 million more people live in Mongolia).
Tip: This to-scale comparison of Alaska vs. Mongolia uses the Mercator projection, which distorts the size of regions near the poles.