If I said a country was 1594719800 metres squared it would mean a lot less to you than if I said it was about the size of Greater London (so long as you know about how big Greater London is). For this reason the media tend to report the extent of a flood in relation to the size of the Isle of Wight or Icebergs in relation to the size of Wales (or Luxembourg) so that we can imagine the extent and scale of a disaster or news story. Despite plenty of comment on how ridiculous such comparisons are, and a great website that will convert standard measurements into the fractions or multiples of the size of Wales, I am yet to see a mapped representation of our increasingly standard units of area. The one I produced above is not meant to be definitive, just a starting point to what I hope will be a new system to replace the metric measures we are used to*.
A much more effective alternative to simply stating an area in terms of its relative size to another area is of course to produce a map. Geographically correct maps contain most of this information in the first place but they generic