I know that this question could sound a little bit dumb since Ryanair always sends lot of emails specifying the dimensions of the allowed hand luggage but I am not interested in the "formal" answer but in the "informal" one.
In every airport where Ryanair flies there is a blue box (baggage sizer) where you and the airport staff can put your hand luggage to test if it can be accepted on board. What I would like to know is the dimension of that box (which is of course bigger than the allowed size).
I've been a pretty frequent Ryanair flyer (one flight per month) and I always used the same luggage which was ok for the old box even if bigger than the allowed size.
Few weeks ago Ryanair introduced the possibility to bring a second hand luggage on board. In doing so they also changed the dimensions of the blue box which now has two compartments (one for the main hand luggage, still bigger than the allowed size, and one for the small one). My old luggage doesn't fit anymore in the new boxes so I guess I'll have to buy a new one, hence the need to know how far can I go with the size of the luggage.