The total weight of life on earth

A group of scientists have written a paper for the U.S. National Academy of Sciences estimating the weight of the different kinds of life on earth.

The total carbon in all living things amounts to 550 billion metric tons, they wrote.  A metric ton is 2,200 pounds.

The weight of all the world’s plants is an estimated 450 billion metric tons.

The world’s bacteria weigh 70 billion metric tons.

All the world’s animals weigh only 2 billion metric tons, of which 1 billion tons consists of arthropods (including insects).

All the world’s humans total a mere 60 million metric tons.

Put another way, life on earth is, by weight, 82 percent plants, 13 percent bacteria and 5 percent everything else, of which 0.01 percent is human life.

Of all the mammals on earth, 60 percent by weight are livestock, 36 percent are humans and 4 percent are wild.

Of all the birds on earth, 70 percent by weight are chickens and other poultry and 30 percent are wild.

The authors of the study estimate that, before there were human beings, there was six times as much wild mammalian animal life, five times as much marine mammalian life and twice as much plant life.

[Added 8/19/2018]  It’s interesting to ponder these facts in the light of what the American land is used for.


Scientists weighed all life on earth by Brian Resnick and Javier Zarracina for Vox.

Humans just 0.01 percent of all life, but have destroyed 83% of wild mammals by Damien Carrington for The Guardian.

The biomass distribution on earth by Yinon M. Bar-on, Rob Phillips and Ron Milo for the Proceedings of the National Academy of Sciences.  PDF version.

Hat tip to


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