Questions asked at the check-in desk

No. Product pages often list the body size without wheels and handles, while airlines measure everything. Measure the bag as it stands and compare it with your airline's own limits.

Choose a hard shell for protection and tidy packing, and a soft bag or backpack for flexibility in tight bins and easy movement over cobbles and stairs. Either works if it fits your airline's limits.

A small bag that fits under the seat in front of you, such as a compact backpack or tote. Limits range from about 40 × 20 × 25 cm to 45 × 36 × 20 cm depending on the airline.

Often, yes. Some carriers cap cabin bags at around 7 to 10 kg and may check at the gate. Weigh your packed bag at home on a luggage scale and keep a small margin.

Only if it compresses to fit the gate sizer. Staff may ask you to test it, and a bulging bag that will not slide in can be sent to the hold, often for a fee. Do not rely on squeezing.

Most airports in the UK, EU and US still use 100 ml containers in a single clear bag (3-1-1 in the US), although some airports with newer scanners are relaxing this. Check your departure and arrival airports.

Not usually. TSA-accepted locks are meant for checked bags. On a cabin bag a small zip clip is plenty, and you should keep valuables on you.

Spend where it counts: wheels, zips and handle on a rolling case, or the stitching and straps on a soft bag. Mid-range bags from established makers often offer the best balance, while premium brands buy durability, warranties and repair support.

Take out medication, passports, electronics, keys and spare lithium batteries or power banks, which must travel in the cabin. Keep a tag with your contact details inside and outside.

If it fits the under-seat dimensions when full, yes on most airlines. A 20 to 25 litre pack is a safe bet on strict carriers; larger packs belong in the overhead allowance.