Interested to see just how much space your population takes up?

Just how tall is that megastructure anyway?

Well, wonder no more. Throw these figures into a handy spreadsheet, or just use pen, paper and a calculator if you're stuck in the 80's and get all the answers you need.

**Population growth**

The simple formula for population growth is this:

(((p1-p2)/p2)*100)/T = % growth rate per year

p1 = your present population

p2 = the population at a point in the past

T = Number of years elapsed since p2

Modern day growth rates are less than 1%, developing nations might reach 3 or 4%, anything more than that would require some narrative explanations.

For example, back in 2016 your population was 10 million, in 2322, you want it to be 80 million. Doing the sum gives you an answer of 2%, an easily obtainable growth rate.

Say you wanted 500 million people; now your growth rate is 16%, steep, but probably explainable with cloning or something or other.

**Population space requirements**

An easy one, work out how much space you want to give each of your inhabitants; the UK rules for HMOs (home with multiple occupancy - flat share) is that 10 m² per person is a reasonable amount of living space (a square just over 3 m on each side). Times this by 5 to allow for non-living space (ultilities, factories, etc. More if you like) then multiply that up by the population involved. A square root of that number will give you the side of the area in metres (it's assuming its a square and only one dimensional).

**Three-dimensional structures**

Get your area figures from the previous sum, multiple this by the height of your storey to get the total volume of a single storied building. Work out how long you want your sides to be. Your height is then volume/(length x width).

Example, you've got 20,000 people you want housed in a mega-structure. Doing the quick calculations, you work out they need 1,000,000 m² of space (20,000 x 50). You make each floor of your structure 5 m in height, so a single storied structure would occupy 5,000,000 m³ (1,000,000 x 5). You want it to be 80 m square, so the total height of your tower is 781 meters, or 157 floors.