The storage capacity of the human brain is around 2.5 petabytes (or a million gigabytes).

(For example, if your brain worked like a digital video recorder there would be enough to hold three million hours of TV shows. You would have to leave the telly running for 300 years to use it all up!  Actually, that would be really good – I’ve nearly run out of my 80 hours recording time!!)

Source – Scientific American