"God can never be accused of skimping or economizing....seven-million-foot height of the city....This statement by John---"according to human measurements"---means this description is to be taken quite literally. That's 2,250,000 square miles, on the ground. Then 1,500 miles up from there! Hang on! Are you ready for this? That's 3,375,000,000 cubic miles, enough room to comfortably accomodate 100,000 billion people!
It has been estimated that approximately thirty billion people have lived in the long history of the world. Even if everyone who ever lived was saved---which is not the case---that would still allow each person 200 square miles on the ground alone...There will be plenty of room for everyone who makes it to Heaven.
And that's just in the city!
(Steven J. Lawson, Heaven Help Us!)