All population data are based on estimates by the UN Population Division and all calculations provided by the UN Population Fund. The remaining data are from other sections of the UN, the Global Footprint Network and the International Telecommunications Union.
Want to find out more? Visit the UN Population Fund's detailed population calculator, 7 billion and me.
Notes on the data: Only birth dates after 1910 can be accommodated and only countries with populations of more than 100,000 people are included. Where available, the UN's medium variant and average figures from 2005-2010 have been used. World and country population clocks are estimates based on the latest UN figures and growth rates. They may not tally precisely with other clocks because of the way this application is configured.
Three country groupings - developed, developing and least developed - featured in the conclusions are those referenced by the UN for assessing the Millennium Development Goals. The transition countries of Eastern Europe have been grouped with developed nations.
Read the answers to frequently asked questions here.