I have this: Ciao Bag Which apparently is no longer available, but it should give you an idea of the size that will fit on an Embraer RJ145. It fits best if you have the wheels facing outwards, but can be shoved the other way too. Most GAs let it on, unless they've decided only one bag person person on the plane (which happens way too often IMO and it's annoying when they make everyone gate check and the overhead bins are all empty). Also, it fits under the seat if you are on a side of the aisle with two seats, but I was unable to jam it under the seat on the side of the aisle with one seat because it is just short of fitting between the bars that come down under the single seat.