Maine is about 3.3 times bigger than Vermont.

Vermont is approximately 23,956 sq km, while Maine is approximately 79,931 sq km, making Maine 234% larger than Vermont. Meanwhile, the population of Vermont is ~625,741 people (702,620 more people live in Maine).
Tip: This to-scale comparison of Vermont vs. Maine uses the Mercator projection, which distorts the size of regions near the poles.