More abstractly, this is a MVC question. Do I put this in my Model, View, or Controller? I think you are saying that the Model (data store) would be the wrong place to start playing with the data, since you've omitted that option. I'm not sure there is a right, or wrong, answer to your question - but I'm not eliminating the Model from the possibilities. Theoretically, if you have a model for this page that is a wrapper around Quota, I don't see it being any worse to say $m->get_limit() vs $m->get_limit_hr() (human-readable). After all, it's your model that would know what the units are that it's returning (is it in bytes, KB, MB, GB, TB? Or is it returning in bits, trits, or some other unit?). I could easily argue that the Model owns the information, and the Controller should merely be asking for the data in the format it needs to pass on to the View.

Of course, I could argue similarly in favour of Controller and View as the owners of the transformation, but which one would be the strongest argument would depend on the rest of your site, and what types of flexibility are important, as well as any other infrastructure you may have (e.g., translations).