How many bacteria are there on Earth?
The standard estimate is 4 to 6 × 10^30 prokaryotic cells — bacteria and archaea together — which makes them by an enormous margin the most numerous organisms on the planet. Most of them are not where you would guess: the majority live in the deep subsurface, in rock and sediment kilometres below the sea floor and the land surface, where they metabolise so slowly that individual cells may divide once a century. Ocean surface water and soil are relatively minor contributors. The figure has held up for a quarter of a century, though deep-subsurface revisions have pushed the low end down somewhat.
How the figure is arrived at
Habitat by habitat: measure cells per millilitre of seawater or per gram of soil using direct microscopic counts with a fluorescent DNA stain, multiply by the volume or mass of that habitat, and add. The deep subsurface dominates and is also the hardest to sample, so nearly all the uncertainty in the total comes from drilling cores.
How confident it is
- Low estimate
- 4,000,000,000,000,000,000,000,000,000,000
- High estimate
- 6,000,000,000,000,000,000,000,000,000,000
- Spread
- 1.5× between the bounds
Other living things and the natural world counts
- How many people are there in the world? about 8.2 billion
- How many grains of sand are there on Earth? roughly 7.5 quintillion on the world's beaches
- How many ants are there in the world? about 20 quadrillion
- How many trees are there in the world? about 3 trillion
- How many insects are there? about 10 quintillion
- How many species are there? about 8.7 million
- How many people have ever lived? about 117 billion
- How many drops of water are there in the ocean? about 27 septillion
- How many fish are there in the sea? somewhere between 3 trillion and 100 trillion — nobody knows
- How many species are endangered? more than 45,000 assessed as threatened
- How many bees are there in the world? roughly 2 trillion managed honey bees
- How many birds are there in the world? about 50 billion wild birds
- How many earthquakes are there each year? about 20,000 located a year — around 55 a day
- How many chickens are there in the world? about 26 billion alive at any moment
Common questions
- How many bacteria are there on Earth?
- about 5 nonillion
- How is that estimated?
- Habitat by habitat: measure cells per millilitre of seawater or per gram of soil using direct microscopic counts with a fluorescent DNA stain, multiply by the volume or mass of that habitat, and add. The deep subsurface dominates and is also the hardest to sample, so nearly all the uncertainty in the total comes from drilling cores.
Related pages
- How many people are there in the world? about 8.2 billion
- How many grains of sand are there on Earth? roughly 7.5 quintillion on the world's beaches
- How many ants are there in the world? about 20 quadrillion
- How many trees are there in the world? about 3 trillion
- How many insects are there? about 10 quintillion
- How many species are there? about 8.7 million
- How many people have ever lived? about 117 billion
- How many drops of water are there in the ocean? about 27 septillion
- How many stars are there in the universe? Space and the universe
- How many countries are there in the world? Things people built
- How many bones are in the human body? The human body
- How many stars are there in the Milky Way? Space and the universe
- How many atoms are there in the universe? Space and the universe
- How many galaxies are there? Space and the universe
Sources
- Typical range compiled from manufacturer specifications — At One Place