The human brain contains approximately 86 billion neurons (brain cells) according to the most recent and reliable scientific estimates
. This figure revises the older, often-cited estimate of 100 billion neurons, which lacked direct empirical support and was more of a ballpark figure
. This estimate comes from a method where brain tissue is homogenized and cell nuclei are stained to differentiate neurons from other brain cells like glia, allowing a precise count of neuronal nuclei that can be scaled to the entire brain
. Studies show some variation in the number of neurons, ranging roughly between 62 billion and 99 billion depending on the individual and method, but 86 billion is the widely accepted average
. In addition to neurons, the brain has a roughly equal number of non-neuronal cells (including glia and other types), challenging the older notion that glial cells outnumber neurons by 10 to 1
. In summary:
- About 86 billion neurons in the adult human brain
- Approximately the same number of non-neuronal cells
- Earlier estimates of 100 billion neurons are now considered overestimates without direct evidence
This refined understanding helps clarify the cellular composition of the human brain and aligns with comparative studies across primates
