What is the size of the milky way galaxy?

Well....The stellar disk of the Milky Way galaxy is approximately 100,000 light years in diameter and about 1,000 light years in thickness.

The entire gaseous cloud is around 10,000 light years thick, increasing to 30,000 light years at the nucleus, and this region extends to about 180,000 light years in total width.

The Milky Way galaxy contains between 200 and 400 billion stars. Most of the stars are on curved "arms" that rotate around the center about once every 250 million Earth years. The Earth is in the Orion Arm of the galaxy, approximately 25000 light-years from the center, or about halfway to the rim.