Anyway, a while back, an email was sent out to the dabney house spam list with subject line "Is that a joke about the size of my brain". The body goes as follows:
"I wondered recently: how much memory (in bits or whatever) can a human brain
store? After some ooming around I figured on 10^11 neurons devoted to
memory. This gives us a lower bound of 10^11 bits (10GB) and an upper
bound of (10^11)! (way too huge). I was hoping to narrow this down a
bit, but I lack the understanding of neuroscience/CNS to know how
neurons store data other than some rough idea that it has to do with
pathways.Failing biologists, we turn to mathematicians. A better
approximation involves assuming that for N neurons each one can only
form connections to any two of its neighboring m neurons (m = 10) and
can form paths of arbitrary length. Throw in a factor of 2 if you want
directed paths. This however involves more math that my tired brain can handle right now, maybe one of you can try that out?-pers"thinks with his thinking apparatus"on "Naturally the best thing to do is to give a well justified, scientifically derived, answer.Aka, let’s see what anime says.

Firstly to simplify the question, let’s restrict to people with eidetic memories, meaning more commonly, perfect recall. I’m assuming that a person with perfect recall has more memory than a person without.

From "To Aru Majutsu no Index" aka "A Certain Magical Index"
The main heroine with perfect recall has 103,000 grimoires loaded in her head from the English Purist Church. Consequently, she needs to wipe her memory every year or she will exeed her memory capacity and die.

Assuming further that a typical magical text is the size of the bible 7.7 Mb–>6.46e7 bits.Multiplied by the number of grimoires, 103000 * 6.46e7 bits –>6.65e12 bits.

Now assuming perfect recall memory renders life at 1080p, Given the movie "A Clockwork Orange", 137minutes, 7G, 1 year –> 26873.258037G–> 2.3e14 bitsIn total, this means in total, she can store 2.4e14 bits in her brain.Impressively, not less than the lower bound (number of neurons in the brain 1e11) and not more than the bekenstein bound. https://en.wikipedia.org/wiki/Bekenstein_bound ( 2.6e42 bits)
Unfortunately, the English Purist Church also says, 10^14 bits is 15% of a brain while
10^12 is 85%

It seems the other characters in the anime also end up realizing the flaw

-Pa"boooooom!!!!!"ul Zhang