How to pack carry-on only

Start with the bag, not the clothes

The single most consequential decision is made before you pack anything: which bag. Buy for the smallest allowance you fly, not the largest, while knowing that no realistic bag is free everywhere. Across the 32 airlines we track, a 40 × 30 × 15 cm bag travels free on 24 of them; universal free carriage means about 33 × 25 × 10 cm, because Lufthansa, Swiss and Austrian cap the free bag at 10 cm deep. Pick the tier you fly most and treat the rest as an occasional fee.

Measure the bag you own rather than trusting the label: manufacturers quote the body, airlines measure the wheels and handles. Put your numbers into the carry-on size checker to see which airlines it actually clears.

Weight is the limit people forget. Several airlines cap the cabin bag at 7 or 8 kg, and that is easier to breach than the dimensions once you add a laptop, a charger and a pair of shoes.

Garment maths

Most over-packing comes from planning per day instead of per cycle. Work in cycles and the numbers flatten immediately:

• Five tops covers a week. It also covers a fortnight, if you wash once.
• Two bottoms, three if the trip spans smart and casual. Jeans do not need washing on a trip.
• Underwear and socks are the exception: bring one per day up to about eight. They are small and the failure mode is unpleasant.
• One pair of shoes on your feet, one in the bag. A third pair is almost never worth its volume.
• One warm layer, one shell. Both worn on the plane if the bag is tight.

The packing list generator applies exactly this in carry-on mode, sized to your trip length.

The toiletries swap

Liquids are the most reliable way to lose a bag's worth of space and the most common reason things get binned at security. Everything must be in containers of 100 ml or less and fit one transparent one-litre bag, and that bag realistically holds 700 to 800 ml of actual containers, because rigid bottles do not tessellate.

Solid shampoo, a soap bar, toothpaste tablets and stick deodorant remove four containers and roughly 400 ml at once, and none of them count towards the liquid allowance at all. Check what is left with the liquids & 3-1-1 calculator.

At the gate

If your bag is borderline, three things help. Wear the bulkiest items: a coat and boots on your body are not in your allowance. Keep the front pocket flat, since depth is what the sizer enforces. And favour a soft-sided bag, which can be compressed into a sizer in a way a hard shell cannot.

If you are asked to put the bag in the sizer, do it without rearranging anything in front of the gate agent. Visibly redistributing weight is what turns a routine check into a thorough one.

Tools for each step

• Carry-on size checker: which airlines your bag clears.
• Packing list generator: quantities in carry-on mode.
• Liquids & 3-1-1 calculator: whether the washbag passes.
• Group trip guide: when several of you are doing this at once.

Common questions