Measure before you fly
Gate agents check carry-ons against a sizer, and a bag that does not fit can cost a checked bag fee at the gate, often more than paying online. Airlines measure the outside of the bag, including wheels, handles and expanded pockets, so the size printed on the label is not always the size that counts.
How the check works
- The calculator sorts your bag’s three dimensions and the limit’s three dimensions from largest to smallest, so it does not matter which side you call the length.
- The bag fits as a carry-on if each dimension is within the matching limit and, when a weight limit is set, the bag is not too heavy.
- Linear size = length + width + depth. A standard checked bag on most airlines may not exceed 62 linear inches (158 cm) and 50 lb (23 kg) in economy.
- Volume in liters = length × width × depth in cm ÷ 1,000.
Example
A carry-on of 22 × 14 × 9 inches, packed to 18 lb:
- Linear size: 45 inches
- Volume: about 45 liters
- Fits the common US limit of 22 × 14 × 9 inches
- 32 lb left before the 50 lb checked bag limit
A larger bag of 24 × 15 × 10 inches exceeds the carry-on limit by 2 inches in length, but at 49 linear inches it can be checked as a standard bag.
Typical limits
- Major US airlines: 22 × 14 × 9 in carry-on, usually with no weight limit on domestic flights, plus a personal item under the seat.
- Many European airlines: 55 × 35 × 25 cm or 55 × 40 × 20 cm, often with a weight limit of 7 to 12 kg.
- Low-cost carriers: often only a small under-seat bag, for example 40 × 30 × 20 cm, is free.
Limits change and vary by fare class, so check your airline’s website before you pack.
Packing tips
- Measure your bag yourself, wheels included, with the front pocket filled.
- Soft-sided bags can be squeezed into a sizer; hard shells cannot.
- Weigh the packed bag with a luggage scale or a bathroom scale (weigh yourself with and without it).
- Put heavy items such as shoes and books in your carry-on only if the airline has no weight limit, and keep medicines, keys and valuables with you.