How big is the Universe?

Nobody really knows how big the Universe is because we cannot see to the edge of it. We don't even know if it has an edge. We can only see out to a distance of about 14 billion light years from Earth. This means that the size of the Universe that we can see is about 28 billion light years in diameter (across). Light has not reached us from beyond this distance. In addition, the size of the Universe is changing and gets larger with time.