I get 4.89 square feet.
The worlds population could live in the state of Texas if you grouped everyone in families of 4, with 75 acres, and a 1500 square foot house.
6.92 billion people in 268581 square miles is over 40 per acre, so if they were grouped in families of 4, every family would have 1/10 of an acre.
Overpopulation of the world is a lie ...
In my lifetime I have seen many negative effects of the increase in population. I'm surprised that you haven't noticed any.
So each person gets an area approximately 33 feet by 33 feet to live on. Plenty of room!
Following up on this, and to clear up some things.
Texas has 261,797 square miles of land area
1 square mile = 27,878,400 square feet, so
Texas has 7,298,481,484,800 square feet of land area.
Divide this by 3000 ft lots,
This gives us:
2,432,827,161 1500 sqft homes on 3000 sqft lots with 756,078,873 houses still empty
The world population is 6,775,235,700 / 4 = 1,693,808,925 households of 4 people each
So this gives us:
2,432,827,161
1500 sqft homes on 3000 sqft lots with 756,078,873 houses still empty
or 81,361 sq miles of open land for streets
So we can put the entire world’s population in the state of Texas with 4 people in a 1500 sqft home on a 3000 sqft lot.
And that leaves over 81,000 sq miles still open.
And of course, the entire rest of the world is free to grow food, have industries, etc.