Carry-on weight limits for major US airlines usually top out at 40 pounds or more, but my definition of light travel does not include a bag that weighs as much as an elementary school student. Because you can carry on 40 pounds doesn’t mean you should. Lifting 40 pounds over your head (or dropping it on your fellow passenger’s head) is no fun. The light traveler should shoot for a packed carryon that slips under the more restrictive weight limits of smaller airlines and international carriers - around 22 pounds. Under 20 pounds will get you comfortably on to almost any plane, and your back, neck, and shoulders will thank you. Get it to 11 pounds (5kg) or under and you’ve passed from lightness to sublimity. And there will be hardly an airline on the planet that will turn your carryon away.