Alaska is about 257 times bigger than Brunei.

Brunei is approximately 5,765 sq km, while Alaska is approximately 1,481,348 sq km, making Alaska 25,596% larger than Brunei. Meanwhile, the population of Brunei is ~478,054 people (232,177 more people live in Alaska).
Tip: This to-scale comparison of Brunei vs. Alaska uses the Mercator projection, which distorts the size of regions near the poles.