If you were around in the 1970s, as I was, you might have heard the following piece of information: “You can fit everyone on earth, standing shoulder to shoulder, in a space no bigger than the Isle of Wight”. I heard this from my older brother, and, as with most information that came from authoritative sources, I didn’t question it. I didn’t do the maths to check if it was true. I remembered it, and repeated it, as you can see.

In 1975, according to this page from worldometers.info, there were 4 billion people on earth, just over half the current total (around 7.8 billion in June 2020). Assuming that the information we were given in the mid-70s was correct, 4 billion people could fit on the Isle of Wight, which Wikipedia tells me is 384 square kilometres (sq km), or 148 square miles. How much more space would the extra 3.8 billion people need? Would the Isle of Man (572 sq km, or 221 square miles) be large enough?

Rather than try to work out the figures for people standing shoulder to shoulder, I have decided to work on the assumption that everyone in the world is social distancing to see how much space we would now need to fit everyone in one place. Assume that everyone is keeping at least 2 metres away from everyone else, in front, behind, to the left and to the right. Assemble the global population in a grid.

• You can fit 500 people in a line 1 kilometre long.
• You can therefore fit 250,000 people (500 x 500) in 1 sq km.
• 1 million people will fit in 4 sq km.
• 1 billion people will need 4,000 sq km (equivalent to a square with sides of 63.3km).
• 7.8 billion people will fit in a space of 31,200 sq km.

And how big is that exactly? It’s equivalent to a square with sides of just under 177km (or 110 miles). It’s smaller than the Netherlands (land area of 33,720 sq km out of a total area of 41,850) or Moldova (for which the relevant figures are 32,850 and 33,846 respectively). It’s also significantly smaller than the Republic of Ireland (land mass of 68,890 sq km), which I can picture much more easily than Moldova. (All of the land areas quoted in this paragraph come from this page from worldometers.info.) In fact, even if the world’s population doubled it could still fit, socially distanced, in the 26 counties of the Republic of Ireland. You wouldn’t need to go north of the border until the global population was way in excess of 17 billion.

By comparison, the number of people that can fit, socially distanced, on the Isle of Wight is just 96,000,000 (96 million). This is less than 2% of the global population. It’s about the same as the number of people in Vietnam. And if you want to fit all 7.8 billion humans in a space the size of the Isle of Wight you will need to squeeze at least 20 people into every square metre. This is not feasible, even for those of us who have commuted on the London Underground at rush hour. So if someone tells you that you can fit everyone on earth into a space the size of the Isle of Wight, tell them that you can’t, not these days, for so many reasons.