square-foot used here not exactly literally I feel but as a way of example, so literal translation does not sound right (in the form proposed above even funny)
Above IS just workaround, CONVEYS THE GIST OF IT and sounds better to me, in view of apparent lack of an established term(?). Can be used one part or the other, or both to be more specific.

I came up with "zair" since more technical than katan/ktantan - the latter perhaps a little derogatory?

Suggest to Google all those options to find an established one, if any, but full text does not bring any meaningful hits, so don't hold yr breath.
Al regel merubaat - gam lo, AZ NELEKH IM HAHUSH HASAFA!