10% of Brain Use

“Most people use only 10% of their brain power.”

I used to hear that all the time growing up. Some people would even say — with mock humility — “I think I’m using 15%,” as if that made them geniuses. Over time, I just stopped paying attention. It didn’t matter to me how much brain power I was supposedly using — what mattered was what I could do with what I had. And honestly, life was good.

But then came the movie Lucy. If you’ve seen it, you know the entire plot hinges on the idea that we use only 10% of our brain, and if we could unlock more, we’d gain superhuman abilities. I watched it, enjoyed it — but that 10% claim got stuck in my head again. This time, I decided to dig a little deeper.

Turns out, the whole thing is a myth — a slick narrative spun by self-help gurus and pop culture, with no scientific backing at all.

Where Did This Myth Come From?

William James

It all traces back (sort of) to William James, a pioneering American psychologist from the early 1900s. In an essay titled The Energies of Men, he wrote:

“We are making use of only a small part of our possible mental and physical resources.”

That’s it. A general observation about human potential. But self-help authors twisted that line into something James never said — the now-infamous claim that we use only 10% of our brain.

The myth really took off when the preface of Dale Carnegie’s How to Win Friends and Influence People wrongly attributed the 10% claim to James. From there, it spread like wildfire.

Science (Sort of)

Early neuroscientists referred to some areas of the brain as “silent,” simply because they didn’t yet understand their function. But “silent” didn’t mean inactive or useless — it just meant “we haven’t figured it out yet.” Unfortunately, many people took this to mean large parts of the brain were doing nothing at all, further feeding the 10% myth.

Einstein? Nope.

Then there’s Albert Einstein. Some versions of the myth claim he supported or even stated the 10% idea. But here’s the truth: Einstein never said anything of the sort. His name was just thrown in to lend the myth some scientific weight — a classic marketing tactic.

So, How Much of Our Brain Do We Actually Use?

Thanks to modern neuroscience and advanced imaging technologies like fMRI and PET scans, we now know the answer: we use 100% of our brain.

Sure, we don’t use every part all at once — just like you don’t use every muscle in your body simultaneously. But over the course of a day, week, or even a single conversation, every region of the brain has a role to play. There’s no vast untapped reserve waiting to be unlocked — your brain is already working full-time.

The Bottom Line

The idea that we only use 10% of our brain is a compelling myth. It suggests hidden potential, superpowers, and a shortcut to greatness — which is exactly why self-help gurus and movies love it. But science tells a different story.

Your brain is already fully active. The real question isn’t how much of it you’re using — it’s how well you’re using it.