How many neurons are in the human brain?
Science medium Data from 2009
Guess before you scroll — the answer is below
The answer
86,000,000,000 neurons
Roughly 86B.
A careful 2009 count put the adult human brain at about 86 billion neurons, retiring the round "100 billion" that textbooks had repeated for decades without a source. Roughly 80% of them are in the cerebellum, which is a fraction of the brain’s volume.
Where this number comes from
| Source | Azevedo et al., Journal of Comparative Neurology |
|---|---|
| Figure refers to | 2009 |
| Last checked | |
| Unit | neurons |
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