The standard US carry-on is 22 × 14 × 9 in, the exact limit of American Airlines, United, Delta and JetBlue. In centimetres that is 55.9 × 35.6 × 22.9 cm. Many European airlines write their limit as 55 cm long, so a case built to the US maximum is 0.9 cm too long for them before you have packed anything.
Which European airlines accept a 22-inch case
British Airways, Virgin Atlantic and Iberia set their cabin bag at 56 cm long, and easyJet sells a 56 cm cabin bag as an extra. A 22 × 14 × 9 in case fits all four, with about 0.1 cm to spare on the length.
Air France, KLM, Lufthansa and TAP Air Portugal stop at 55 cm. Air France and KLM are also only 35 cm wide, so the same case is too long and too wide for them. Icelandair, and Ryanair for its paid bag, add a 20 cm depth limit, 2.9 cm less than the 9 in of a US case. Aer Lingus includes its 55 × 40 × 24 cm cabin bag on transatlantic flights, but sells it as an extra on the Saver fare on its other flights.
Why 0.9 cm matters
Our checker treats every published limit as exact. It shows a hard case that is over a published side as too big, and a soft bag over by 1 cm or less on a single side as risky, never as fitting. The four US airlines in this guide accept the same case exactly at their limit, so the 0.9 cm only matters on a European airline.
Weight appears in Europe
American Airlines, United, Delta and JetBlue publish no weight limit for the carry-on on these fares. Most European airlines in this guide do: 8 kg on Lufthansa, 10 kg on Iberia, Virgin Atlantic, TAP Air Portugal and Icelandair, and 12 kg for both bags together on Air France and KLM. A bag packed without weighing it in the US can be over on the way back.
One bag for both sides of the Atlantic
The figures below give the largest bag that all fifteen airlines accept. A 55 cm case that is no more than 35 cm wide and 20 cm deep, weighed before each flight, works on every one of them, including the low-cost connection you may add inside Europe.