As of 2011, about how large was the world's human population, and about how long will it take to add another billion

The annual population growth rate is a rate that is estimated based on past years and the expected rate for the future. To find out how long it will take to add another billion to the population, we must first know how large the world’s human population was in 2011. The annual percentage growth rate is normally between 1% and 2% but commonly stays under 1.2%.

As of 2011, the world's population has reached 7 billion. The annual population growth rate is 1.2%, thereby there would be an additional 1 billion population growth at approximately 11 years or by 2021 the population would be 8 billion.