This may take many years to be answered, if it’s ever done. Our brain processes information in a way that is very different from regular computers. We’re only just starting to understand how it stores memories and how these memories are linked together. Many people tried to make estimates about how it would compare to a computer, and common estimates range between one and ten terabytes (1,000 gigabytes). Others believe it is far greater at about two petabytes (a million gigabytes). Some think it’s actually much smaller, and our brain is just much more efficient than computers at storing information.
José Monteiro, Science Museum