Never understood why you'd need a Death Star, when one of the
Incredible Cross-Sections books gives the turbolasers on an average-sized troop transport a 200
gigaton per shot yield.
For reference:
The fireball would be 40 miles wide, concrete buildings 100 miles from the hypocenter would be demolished, and people 1,000 miles away from the blast would receive third degree burns.
But yeah, the Death Star is big and scary.