An adult human brain has about 86 billion neurons (nerve cells) and a similar number of non‑neuronal cells (like glia), for a total of roughly 170 billion brain cells.

Quick Scoop: Key Numbers

  • Neurons: ≈ 86 billion.
  • Non‑neuronal cells (mainly glial cells and others): ≈ 85 billion.
  • Total brain cells: on the order of 170 billion (neurons + non‑neurons).
  • Older textbooks often said “100 billion neurons,” but newer counting methods revised this to ~86 billion.

Why the Numbers Changed

For many years, neuroscientists repeated the “100 billion neurons” figure without a solid direct measurement behind it.

More recent work using improved counting techniques (notably studies by Suzana Herculano‑Houzel and colleagues) measured an adult human brain and found about 86 billion neurons and 85 billion non‑neuronal cells.

A Sense of Scale

Each neuron can form thousands of connections (synapses) with other neurons, leading to up to around 1 quadrillion connections in total.

This vast network is what underlies memory, thought, emotion, and behavior, so the “how many brain cells” question is really about the immense complexity of that network, not just the raw count.

TL;DR: A typical human has about 86 billion neurons and roughly the same number of other brain cells, for around 170 billion brain cells in total.