How many species have been formally described by science?
Guess before you scroll — the answer is below
The answer
2,160,000 species
Roughly 2.2M.
Science has named about 2.16 million species. Estimates of how many actually exist range from 8 million to over a trillion once microbes are counted, so we have plausibly catalogued well under a quarter of visible life — and a rounding error of the rest.
How to get close to this number
Build from the groups. Insects alone account for over a million described species, plants a few hundred thousand, and everything else — fungi, molluscs, vertebrates, microbes — adds several hundred thousand more. Summing the major groups lands you around two million.
The uncertainty in the explanation is the genuinely humbling part: estimates of how many species exist range from eight million to over a trillion once microbes are counted. That is not a narrow disagreement; it is five orders of magnitude, and it means nobody knows within a factor of a hundred thousand how much life there is.
The reason is that most life is small and unobserved. Cataloguing requires someone to find, collect and formally describe an organism, and the rate of description is limited by the number of taxonomists rather than by the number of species. The catalogue measures scientific effort, and the gap to reality is a measure of how much effort remains.
Where this number comes from
| Source | Catalogue of Life |
|---|---|
| Figure refers to | 2024 |
| Last checked | |
| Unit | species |
Numbers move. If this one has drifted from its source, let us know.
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