Beginning with (Lucid) 10.10, Ubuntu began using base-10 to represent storage sizes. For me, working with Windows all day and then going to work on my Ubuntu notebook, it is very irritating to have to calculate values sometimes. I understand that it is the recommended policy to use base-10 (GB), but I am all too familiar with base-2 (GiB, or GB on Windows) and I blame Windows. So here is my question:
Is it possible to switch Ubuntu's Units policy to base-2 and if so, how?
The only way to do this, would be to patch (or in some cases, un-patch) all of the code which displays sizes to the user, and recompile your own fork of Ubuntu which has all of the sizes displayed using base 8 math (which is what you are asking for, and not base 2). It is a very invasive change to make, and is not an Ubuntu specific thing, as upstream applications were already doing this. The Ubuntu policy on size display is merely to clarify the matter, and to provide an official stance.
There is no setting which will switch between GiB and GB in all applications. If that's what you're looking for, the only way you're going to get it is to maintain patches to everything, which does so; unless you can convince all the upstreams to use such a setting, and provide patches, which they accept.
I'm sorry if you're looking for a simpler solution, but it doesn't exist, and isn't likely to anytime soon.
It is possible for KDE apps.
Just change it in your system settings.
First, install systemsettings clicking this
then, run it
Then, choose Locale ▸ Other ▸ Byte Size Units
select the one you want.
I don't believe this is possible without switching to a previous version of Ubuntu.
Edit
Unless you want to compile it yourself in base-2 :) You might gain some fans
The first step would be to open bug reports for every affected package, and secondly send it upstream to be fixed.
Ubuntu does have a "Units Policy" so this is a very-long-term plan (I assume).
https://wiki.ubuntu.com/UnitsPolicy
https://bugs.launchpad.net/ubuntu/+bugs?field.tag=units-policy