Know the limits
Most large US airlines allow a carry-on of about 22 by 14 by 9 inches, wheels and handles included, plus a personal item that fits under the seat, and they rarely weigh either. Abroad, the box is often smaller and the weight matters. Limits of 7 to 10 kilograms, roughly 15 to 22 pounds, are common in Europe and Asia and are enforced with a scale at the gate. The cheapest fare on some airlines includes only the under-seat item. Read the baggage rules for every carrier on the trip, then measure and weigh the bag packed rather than empty.
What goes in
A week of clothing in two or three colors that all go together covers a trip of any length. A workable count is four or five tops, two bottoms, one warm layer, a light rain shell, underwear and socks for five days, and two pairs of shoes including the pair on your feet. Wear the heaviest shoes and the jacket onto the plane. Wool and synthetic fabrics dry overnight, and denim does not. Wash small items in the sink, roll them in a towel, press out the water and hang them up. Once a week, a laundromat or a wash-and-fold service handles the rest for a few dollars.
Liquids and forbidden items
Liquids in a carry-on must be in containers of 3.4 ounces, or 100 milliliters, all fitting in one quart-size clear bag. Solid versions sidestep the rule: a fragrance-free bar soap, a shampoo bar, stick deodorant and toothpaste tablets. Buy sunscreen when you land. Some things cannot come at all without a checked bag, including knives, multi-tools with blades, hiking poles and full-size liquids. The Transportation Security Administration keeps a searchable list of what is allowed. Spare lithium batteries and power banks run the other way, since they are permitted only in the cabin.
The gate-check problem
On a full flight, the last boarding groups have their bags taken at the jet bridge and put in the hold. Keep medication, passport, batteries, electronics and valuables in the personal item, so that you can hand over the larger bag in ten seconds without repacking on the floor. Board when your group is called rather than lingering in the lounge, because bin space goes to whoever gets there first.
Tip Do a trial pack a week ahead, then remove three things. Nobody comes home wishing they had carried more.
