How many square meters occupy a single person?

Answer 1

0.4

Assuming we are talking about people standing up ...

In a recent article about counting crowds, it was stated that when people standing are very close together, each person will occupy about 2.5 square feet. People in a real crowd won't feel comfortable standing so close together, and will each take about 5 ft2.

1 ft2 is about 0.092903m2, so these values translate to about 0.23 and 0.46 respectively. A good straightforward answer would be about 0.4 m2.