I was thinking how, with a laptop you must take it out of the bag and place in the tray to go through security. This may seem a bit bulky and large with iMac? I have heard others have carried on 20" iMacs, so the new 21.5" is not all that much larger. It appears the total measurements of length + width + depth of the carry-on bag with the 21.5" iMac are 45.5" this is only stretching the carry-on max rule of 45". Though I notices some airlines state the width of the bag being less. So, I am planning to go to Australia with my iMac (moving there) and would like to know if anyone in the Mac community has traveled with a 21.5" iMac as a carry-on. Any thing else you can tell me about it would be great!