There are a lot of ways to estimate the amount of information stored on the internet, but we can put an interesting upper bound on the number just by looking at how much storage space we (as a species) have purchased.
The storage industry produces in the neighbourhood of 650 million hard drives per year. If most of them are 3.5″ drives, then that’s eight litres (two gallons) of hard drive per second.
This means the last few years of hard drive production-which, thanks to increasing size, represent a large chunk of global storage capacity-would just about fill an oil tanker. So, by that measure, the internet is smaller than an oil tanker.