Backpack Size Rules by Airline
Cabin allowances split into two figures: a personal item that goes under the seat and a cabin bag that goes overhead. European budget carriers cluster around 40 by 30 by 20 centimetres for the under-seat bag; large US carriers mostly use 18 by 14 by 8 inches, and United does not.
Every carrier covered here
| Carrier | Personal item | Cabin bag |
|---|---|---|
| Ryanair | 40 × 30 × 20 cm | 55 × 40 × 20 cm |
| Wizz Air | 40 × 30 × 20 cm | 55 × 40 × 23 cm |
| easyJet | 45 × 36 × 20 cm | 56 × 45 × 25 cm |
| Vueling | 40 × 30 × 20 cm | 55 × 40 × 20 cm |
| American Airlines | 45.7 × 35.6 × 20.3 cm | 55.9 × 35.6 × 22.9 cm |
| Delta Air Lines | 45.7 × 35.6 × 20.3 cm | 55.9 × 35.6 × 22.9 cm |
| United Airlines | 43.2 × 25.4 × 22.9 cm | 55.9 × 35.6 × 22.9 cm |
| Frontier Airlines | 45.7 × 35.6 × 20.3 cm | 61 × 40.6 × 25.4 cm |
Allowances differ by carrier, by fare and sometimes by aircraft, and they change without notice. Every figure here is the one the carrier published when this page was last reviewed; check the measurement on your own booking before you fly.
Why the two figures differ so much
A personal item is defined by the space under an aircraft seat, and a cabin bag by the overhead bin. The under-seat figure is the one that varies, because seat pitch and the box beneath it differ by aircraft as much as by airline, and because it is the allowance carriers use commercially. The overhead figure is close to standard: 55 or 56 centimetres long across most of the industry.
Two numbers are worth memorising. In Europe, 40 by 30 by 20 centimetres clears every budget carrier listed here. In the United States, 18 by 14 by 8 inches clears every carrier here except United, whose 17 by 10 by 9 is four inches narrower.
Packing to the tighter figure
On a trip that mixes carriers, pack to the smallest allowance on the itinerary rather than the one at departure. A bag that clears an American gate at 18 by 14 by 8 will not go into a Ryanair sizer, and finding that out at the gate costs a fee that is usually larger than the fare difference that made the flight attractive.
The mechanics behind all of this — what a sizer measures, which dimension fails first — are in the personal item size guide, and the two allowances are compared in carry-on versus personal item.