The human brain is an amazingly complex and powerful neural supercomputer that rivals any computer than man can build — it is lightning fast (processing speed of 2.2 billion megaflops), has enormous memory capacity (2.5 petabytes or 2.5 quadrillion bytes), very small (the average human brains is 6 inches long and weighs 3 pounds), utilizes efficient parallel computing (the brain contains 100 billion neurons and a hundred trillion synapses; while a computer stores data as bits using a zero or a one, the brain recognizes 26 synaptic strengths that correspond to storing 4.7 bits of information at each synapse), and consumes very little energy (20 watts). To better understand the human brain’s massive memory capacity, 2.5 petabytes is equivalent to 50 million four-drawer filing cabinets filled with text. If 1 petabyte is equal to 10,000 hours of television programming, then 2.5 petabytes is equivalent to 25,000 hours of TV programming; and it would take 16 years of nonstop TV watching to get through all that content. Or consider this analogy: the Milky Way consists of about 200 billion stars. If each star was a single byte, we would need 10,000 Milky Way Galaxies to reach 2.5 petabytes. Now that’s what you call star power!
Currently the fastest supercomputer is the Tianhe-2, located at the National Supercomputer Center in Guangzhou, China, that was developed by China’s National University of Defense Technology. The Tianhe-2, built at a cost of $390 million, has a processing speed of 33.86 petaflops (quadrillions of calculations) per second. The supercomputer utilizes 16,000 computer nodes with a total of 3.12 million cores and draws 17.6 megawatts of power. (Biochemical pathways are extremely efficient; in general a computer, that uses electrons flowing in a wire generating heat, requires 50 million times more energy to complete the same task as a human brain.) The computer’s memory holds 12 tebibytes (1.024 million GB) of data and has a storage capacity of 12.4 petabytes. The supercomputer occupies a 720 square meter footprint.
To give you some idea of just how powerful the human brain is as a computer, researchers at the Okinawa Institute of Technology Graduate University in Japan, used the K computer, the fourth fastest supercomputer in the world (rated at 10.51 petaflops), to simulate a single second of human brain activity. It took the K computer 40 minutes using 82,944 processors and about 1 petabyte of memory to simulate just one second of human neural processing time.
For further reading: https://www.verywell.com/how-big-is-the-brain-2794888