World Population Clock
Notes on World Population Clock and World Vital Events
Note: Date of data updated.
The populations displayed on the World Population Clock are not intended to imply that the population of the world is known to the last person. The World Population Clock is only an estimate of the world population and an indication of how fast it is growing. According to the current estimates, the world population reached 6 billion on 21 June 1999 at about 4.25 PM GMT (June 21 at 12.25 PM EDT). Given the uncertainties of the estimates and the fact that estimates are constantly updated, it is possible that the estimate of when the 6 billion was hit could change. The United Nations, whose population estimates differ somewhat from our figures, celebrated the "Day of 6 Billion” on 12 October 1999.
The estimates and projection of the world population used to produce these figures were developed by the International Program Center (U.S. Bureau of the Census, Population Division)1 based on analysis of available data on population, fertility, mortality and migration. The analysis is performed separately for the 227 countries or areas of the world with a population of 5,000 or more based on information from census, survey and administrative records. For most countries and especially less developed countries, adjustment of the data is necessary to correct errors, omissions and inconsistencies in the data. Since the most recent data for each country is at least two years old (for most countries they are even older), the populations used are projections from these estimates based on assumed trends in fertility, mortality and migration. As new data become available, all data are reevaluated and some data changes may be made. For general information about how these estimates and projections are made, please see Appendix B of the report, World Population Profile: 1998. These estimates and projections are contained in the International Data Base.
The World midyear population and vital event estimates result from an aggregation of the figures for the individual countries and areas. The intermediate population estimates are based on a linear interpolation between successive midyear population figures. World vital events for different units of time are computed based on the number of months, days, hours, minutes or seconds in the given year.
Figures may not add to totals due to rounding.
- U.S. Census Bureau, Population Division International Programs Center
- U.S. Census Bureau, International Data Base