First Contact With Carry-On Rules

Carry-on rules have quietly become one of the most confusing parts of modern travel. Every airline has slightly different sizes, weight limits, and personal item allowances. And European low-cost carriers have made a small business of catching passengers at the gate.

The good news is that once you understand the categories, you can pack a bag that works for almost all of them.

The size that fits almost everywhere

The near-universal carry-on standard is 55 x 40 x 23 centimeters, or roughly 22 x 14 x 9 inches. This fits in the sizer bin at almost every major airline in the world. The exceptions are important.

Ryanair, easyJet basic, Wizz, and some other low-cost carriers now sell a base fare that only includes a small personal item, 40 x 20 x 25 centimeters, that must fit under the seat in front of you. Adding a full-size carry-on costs 15 to 40 euros extra. Book without adding it and try to bring a normal carry-on and they will catch you at the gate.

Some airlines have weight limits on carry-ons, even in economy. Emirates and Qatar allow 7 kilos. Ryanair's paid-priority carry-on allows 10. Cathay allows 7. Many US carriers have no strict weight limit and enforce it based on whether you can lift the bag yourself.

The personal item

The personal item is the small bag that fits under the seat in front of you. On most airlines this is genuinely useful. On low-cost carriers, it's often the only free bag you get.

A good personal item is 40 x 20 x 25 centimeters or slightly less, structured enough to hold shape when full, and organized so you can grab your laptop, passport, water bottle, and headphones without unpacking the whole thing.

The Aer Travel Sling, the Peak Design Everyday Sling, the Cotopaxi Allpa in the smaller sizes, and various minimalist packs in the 15 to 20 liter range all work well.

Choosing the actual carry-on

The debate between soft-side and hard-shell has some real trade-offs.

Soft-side bags like the Osprey Farpoint, Tortuga Travel Backpack, or Peak Design Travel Backpack are lighter, more forgiving of tight overhead bins, and easier to squeeze into a sizer. They also give you more usable interior space for the same external dimensions.

Hard-shell bags like the Away Carry-On, Rimowa Essential Cabin, or Monos Carry-On are more protective of fragile items, roll better on smooth floors, and look nicer. They're heavier, less forgiving of odd overhead bins, and a small dent can be permanent.

For most travelers doing one to two-week trips, a backpack-style carry-on wins on flexibility. For frequent business travel where you're rolling through terminals, a hard-shell with good wheels wins.

The 100 ml liquid rule and its exceptions

The 100 ml liquid rule is still in force at most airports. All liquids in a single 1-liter clear zip-top bag, containers no larger than 100 ml each.

Newer CT scanners at some airports mean you no longer need to remove the bag or your laptop. This is now standard at London City, Amsterdam, Frankfurt (some lanes), Rome, and increasingly the US TSA lanes. Watch what the person in front of you does or just ask the officer.

The EU announced in 2024 that some airports would remove the liquid rule entirely with the new scanners, then partly walked it back. Assume the rule still applies unless clearly told otherwise at the specific airport you're leaving.

Medications and baby food are exempt from the 100 ml limit. Declare them at the checkpoint.

Things that catch people out

• Powder-form items over 350 ml. This includes protein powder, some dry cosmetics, and some spices. Rarely enforced but occasionally is.
• Lithium batteries. Spare batteries and power banks must be in carry-on, never checked. This includes power banks in your rolling suitcase if you happen to check it.
• Solid food. Fine everywhere except when crossing certain borders where agricultural rules apply. Meat and dairy into Australia, New Zealand, and the US will be seized.
• Corkscrews and multitools. Small ones without blades are usually fine. Anything with a blade needs to be checked.
• Aerosols. Deodorant sprays and dry shampoo often trigger extra screening. Consider stick or roll-on versions.

Packing to actually use the space

The single biggest packing improvement is a set of compression cubes. Something like Peak Design's or Eagle Creek's compression sacks lets you fit about 30 percent more clothes in the same bag by squeezing air out.

Pack heavy items at the bottom near the wheels. Shoes at the outside edges. Anything you need mid-flight, headphones, book, snacks, medication, in the personal item or the top pocket of your carry-on.

Roll clothes if you're a roller, fold and stack if you're a folder. Rolling gains a little space and creates less wrinkles for most fabrics. Folding is faster.

The gate check trap

If a flight is full and the crew announces they need volunteers to gate check bags for free, that's usually a fine deal. Your bag rides in the hold, comes out on the belt at destination, and you didn't pay a checked bag fee.

If the crew forces gate checking because the overhead bins are full, take out anything valuable, fragile, or essential. Laptops, cameras, passports, medications, phone chargers. That bag might not appear for 40 minutes at arrival.

Frequent travelers with lounge or priority boarding rarely get gate checked. If you don't have status, board earlier by paying for priority or checking in the moment online check-in opens.

The one-bag person

There's a small subculture of travelers who go carry-on only for every trip, including two-week ones. They tend to have opinions about their bag choices.

The one-bag principle boils down to a few rules. Buy fewer, better clothes that mix and match. Wear the heaviest items on the plane. Use a merino wool base layer that can go three days between washes. Wash things in the sink or a hotel bathtub. Bring a universal power adapter, not one per device.

You end up with less stuff and more freedom. No baggage claim wait. No checked bag fees. Nothing lost by the airline. And a bag light enough to jog to the gate with when you need to.