The world population is almost 7.8 billion. According to the United Nations, this figure was reached on October 31 in 2011. But can we be sure? What is the margin of error?

We have population figures for all countries of the world, though their accuracy varies. They enable us to estimate the total number of humans on earth to within a few percentage points. The figure of 6.5 billion may have been reached one or two years before 2011. We nonetheless have a clear picture of overall demographic trends and can confidently predict that the world will count between around 10 billion people in 2050.

Source: Projections by continent INED