Is the Human Brain a 100 THz Computer?

People often say the brain is like a 100 THz supercomputer because it has 100 billion neurons firing at 1 kHz. But that’s not how the brain really works. 

 

Here’s why this comparison is misleading and what makes the brain far more remarkable.

You’ll often hear claims like  

“The brain has 100 billion neurons, each firing at about 1 kHz — so it’s a 100 THz computer!”

It’s a fun idea, but this analogy doesn’t really fit.

A CPU runs a precise sequence of digital instructions, all synchronized by a clock signal.
A neuron, by contrast, communicates through electrical spikes that happen irregularly — typically tens or hundreds of times per second, not thousands — and each neuron connects to thousands of others. The brain is a massively parallel, analog, and asynchronous network, not a clocked processor.

If we multiply neurons by their average firing rate, we get around 100 trillion (10¹⁴) “events” per second, but these events aren’t bits flipping; they’re complex biological interactions that change connection strengths and process information in dynamic, adaptive ways.

Researchers estimate that the brain performs about one quadrillion (10¹⁵) synaptic operations per second, roughly on par with today’s exascale supercomputers, yet it does so using only around 20 watts of power.

So while the “100 THz brain” makes for a catchy headline, the truth is even more impressive: the brain’s magic lies not in its clock speed, but in its massive parallelism and energy efficiency.

And here is a two-part infographic comparing the human brain to supercomputers.

A table showing the brain performing 1 exaSOPS (10¹⁵ synaptic operations per second) on 20 watts versus Frontier supercomputer delivering 1.1 exaFLOPS on 30 megawatts.

A bar-and-line chart illustrating that the brain achieves 10¹⁵ operations/second on 20 W, while even hypothetical future AI chips reach only 10¹² at 20–30 MW, making the brain roughly a million times more energy-efficient than silicon. Icons of a brain and a server rack emphasize the power difference.