How Much Would it Cost to build the Death Star?

We began by looking at how big the Death Star is. The first one is reported to be 140km in diameter and it sure looks like it’s made of steel. But how much steel? We decided to model the Death Star as having a similar density in steel as a modern warship. After all, they’re both essentially floating weapons platforms so that seems reasonable.

What? A battleship has to support its own weight and float in the water. That puts an upper an lower bound on its average density. A Death Star is assembled in space. The only thing it has to support itself against is gravitational collapse, and you have sci-fi technologies like tractor beams and force fields and hyperspace travel.

[A]t today’s rate of steel production (1.3 billion tonnes annually), it would take 833,315 years to produce enough steel to begin work. So once someone notices what you’re up to, you have to fend them off for 800 millennia before you have a chance to fight back.

This is the Galactic Republic/Empire, not one planet! I don’t know if there’s a definitive source, but indications are that there are more than a million member worlds with many times that number of colonies.

Oh, and the cost of the steel alone? At 2012 prices, about $852,000,000,000,000,000. Or roughly 13,000 times the world’s GDP

But, as we see, less steel and many, many planets from which to draw resources.