The UN Population Fund is projecting that the world's population will hit seven billion around October 31, but the US Census Bureau begs to differ just a little bit.

The federal government agency, which Friday around 4 pm (2000 GMT) put the total number of people on Earth at 6,971,347,580, reckons the milestone will only be reached on March 12 next year.

"Although these dates differ, world population estimates of the two organizations, which are done independently of each other, are very close -- currently within 0.4 percent of each other," it said in an email to AFP.

"The increase in the worlds population is due to the excess of births over deaths," it added. "The Census Bureau estimates of this excess in recent decades is similar to that of the United Nations, yet slightly lower."

It also cautioned that census data may not fully cover a country's population, while the quality and availability of demographic sources can differ between nations as well.

The US Census Bureau sees the world's population reaching 7,023,324,899 by July 1 next year, according to its World POPClock Projection website (www.census.gov/population/popclockworld.html).