Mauritania is about 1.4 times smaller than Alaska.

Alaska is approximately 1,481,348 sq km, while Mauritania is approximately 1,030,700 sq km, making Mauritania 69.58% the size of Alaska. Meanwhile, the population of Alaska is ~710,231 people (3.5 million more people live in Mauritania).
Tip: This to-scale comparison of Alaska vs. Mauritania uses the Mercator projection, which distorts the size of regions near the poles.