Question

How many light years across is the universe?

Answer 1

13.7 billion years

The universe is about 13.7 billion years old. Light reaching us from the earliest known galaxies has been traveling, therefore, for more than 13 billion years. So one might assume that the radius of the universe is 13.7 billion light-years and that the whole shebang is double that, or 27.4 billion light-years wide.about 93 billion light years  the observable Universe is, of course, much larger. According to current thinking it is about 93 billion light years in diameter.

Answer 2

13.7 billion years .........