The memory capacity of the human brain is for sure unlimited.

Dear @Sundar, another commonly cited estimate puts the figure at closer to 100 terabytes of storage. Slate's Forrest Wickman explains the reasoning behind this number, reading follows!

http://io9.com/if-your-brain-were-a-computer-how-much-storage-space-w-509687776

http://io9.com/5974883/is-it-time-to-move-past-the-idea-that-our-brain-is-like-a-computer

I´m not able to calculate the memory capcity of the human brain very quickly. But I´ve read a very important fault in the original question. We possess about 100 Billions of neurons, so each calculation based on the 1 Billion cells must be totally wrong.

Brains aren’t exactly like computers, though both do handle many computations per second. An article on Think Quest theorizes that the brain is capable of about 100 million MIPS (million computer instructions per second), based on some complicated estimations. But there’s no way to actually measure how much processing power a human brain has, and there’s a similar problem when it comes to determining its storage space. There are a few theories, however.

One theory from an article on io9.com explains that there are about 100 billion neurons, and each is capable of making about 1,000 connections that represent 1,000 synapses (synapses do the work of data storage). If you multiply each of the 100 billion neurons by the 1,000 synapses, you get 100 trillion data points, or 100 terabytes of info. The problem with this theory is that each synapse could potentially hold more or less than the one byte of information assumed in this formulation.

The next theory (from the same article) estimates that the brain’s memory capacity is closer to 2.5 petabytes or 2,500 terabytes (equivalent to about three million hours of TV shows or about 2.2 trillion puppy pictures). In the theory we discussed, each synapse was responsible for one data point, but because neurons actually help with many memories at a time, this theory suggests that the number increases greatly because the data isn’t restricted to a single point.

http://www.storagecraft.com/blog/if-the-human-brain-were-a-hard-drive-how-much-storage-capacity-would-it-have/

Dear Hanno Krieger - I quoted Paul Reber's views from Scientific American published in 2010. After your correction, I checked other sources, and an interesting article published in Nature (2013) gives a better estimate of the number of neurons in the human brain. Some excerpts from the Nature article:

"For a long time, neuroscientists would say that there are about 100 billion neurons in the human brain. Interestingly, no one has ever published a peer-reviewed scientific paper supporting that count. Rather it's been informally interpolated from other measurements. A recent study from 2009 published by Azevedo and colleagues took a crack at a more precise estimate. Their answer?

Approximately 86 billion neurons in the human brain. The latest estimates for the number of stars in the Milky Way is somewhere between 200 and 400 billion. So close, but the human brain certainly doesn't quite stack up!

But why do scientists think there are 86 billion neurons? How did they get that number? Well the easiest way to estimate the number of neurons in the brain is to count how many are in one part of the brain and then extrapolate out for the rest of the brain's volume.

Interestingly, this method can also be used to estimate how many stars are in the Milky Way!"

http://www.nature.com/scitable/blog/brain-metrics/are_there_really_as_many

It is yet to be fully worked out in a definitive terms. However, the storage capacity of the brain in electronic terms is thought to be upto 1000 terabytes. The National Archives of Britain, containing over 900 years of history, only takes up 70 terabytes, making human brain’s memory power pretty impressive.

The memory capacity of the human brain is for sure unlimited.

Dear Abedallah,

by sure not. Our brain has a limited capacity. Its huge, but limited. And btw, it´s good not to store all our experiences. It´s well done that we sometimes forget bad facts. This keeps us healthy.

Dear Hanno Krieger - I fully agree with your view that it is not good to store all our experiences in our brain. In this context, I like to recall a famous conversation between Sherlock Holmes and Dr. Watson in their first joint adventure- "A Study in Harlet".

Excerpts below ("A Study in Scarlet" - Sir Arthur Conan Doyle):

Dr. Watson writes on Sherlock Holmes..

His ignorance was as remarkable as his knowledge. Of contemporary literature, philosophy and politics he appeared to know next to nothing. Upon my quoting Thomas Carlyle, he inquired in the naivest way who he might be and what he had done. My surprise reached a climax, however, when I found incidentally that he was ignorant of the Copernican Theory and of the composition of the Solar System. That any civilized human being in this nineteenth century should not be aware that the earth travelled round the sun appeared to be to me such an extraordinary fact that I could hardly realize it.

"You appear to be astonished," he said, smiling at my expression of surprise. "Now that I do know it I shall do my best to forget it."

"To forget it!"

"You see," he explained, "I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things so that he has a difficulty in laying his hands upon it. Now the skilful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones."

"But the Solar System!" I protested.

"What the deuce is it to me?" he interrupted impatiently; "you say that we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or to my work."

Treating every brain is capable enough to be "as equal", Top 10 Ways to Improve Your Memory

The human brai­n is like a library that stock­s memories instead of books. In some ways, that makes the hippocampus, the part of the brain most involved in memory, the brain's librarian. The hippocampus has the most responsibility in this cranial library, juggling the new releases of short-term memory while cataloging materials for the permanent collection of long-term memory. It's not the only part at work, however, in storing these chapters of our lives. Different kinds of memory are stored in different areas of the brain.

http://www.discovery.com/tv-shows/curiosity/topics/10-ways-to-improve-memory/

Dear Sundarapandian

The human brain is the most complex living structure known in the universe. Measuring the human brain capacity is a matter of difficulty because the degrees of permanence among memories varies.

Dear @Hanno, it is better for human not to remember every thing, but they can remember and create many things. 

I remember many RG friends - especially those who answer me like eminent Prof. Mahfuz, and other friends like Abedallah, Krishnan, Roland, Kamal, Mohammad, etc. There are many others also who reply to me but the list is too long. Prof. Nageswara Rao and Debi seem to be very busy these days.. I hardly see any replies from them..

We all can learn from each other and live in harmony as in Nature (kindly refer to my query today).

Efficient memory use requires accurate metamemory: the processes that monitor states of learning, knowledge, and skill, and also control the deployment of mnemonic and other cognitive processes to achieve desired states. That is, one must be able to make accurate judgments about one's current memory state and predictions about future states, and exercise judicious control over the various options at one's disposal, including encoding and retrieval strategies, study time allocation, item selection, and scheduling of study repetitions. Our research investigates the monitoring and control processes that comprise metamemory by focusing on factors that moderate metamemory performance, such as: prior knowledge, task goals and expectations, time pressure, and stimulus characteristics. For example, we are interested in the conditions under which one exhibits "learning to learn"--adaptively calibrating metamemory in order to more effectively assess and deploy memory resources in the context of a specific task. Our interests also concern the development of ever more sophisticated and rigorous approaches to the analysis and measurement of metamemory.

Prof. Krishnan's reference to "metamemory" got me very interested.

I have enclosed link of a web-page that gives a good number of references about metamemory. Some excerpts from this link:

Put simply, metamemory is knowledge about memory. More specifically, it is knowledge about how your memory works, the contents of it and how to regulate it. The more you understand about the functioning of memory, the easier it will be to benefit from instruction in your memory skills. There are four aspects of metamemory which play a huge role in memorization and learning no matter what age you are.

• The first aspect is factual knowledge about how memory works.
• The second aspect is memory monitoring which is being aware of how you use your memory and the state of it.
• The third aspect  is memory self-efficacy, or how well you think you use your memory in stressful or demanding situations.
• The last aspect is memory-related affect which is the emotional states related to the demanding situations.  

http://faculty.mercer.edu/spears_a/studentpages/webpagesfall09/metamemory/webpage.html

As far as memory capacity of human brain is concerned, facts and figures are very fuzzy. The actual capacity in number of memories is still extremely difficult to calculate because we neither have precise estimates on the number of neurons needed to store a single memory nor how effectively they combine exponentially. But probabilities still are the limiting factor on information in human brain is the learning rate not the amount the brain can hold.