Luggage size restrictions vary between airlines and sometimes between domestic and international routes. It’s worth checking the regulations on every leg to play it safe.
Most airlines measure check-in luggage in linear dimensions, which means the sum of the length, width and height. The most common linear limit for check-in luggage is 62 inches, though it’s prudent to confirm. EasyJet, for example, allows up to 108 linear inches (275 cm) for check-in bags, while United Airlines permits 62 linear inches (157 cm) — that’s a pretty significant difference.
Some carriers, however, forgo linear dimensions in lieu of specific size restrictions for each check-in bag dimension. British Airways, for example, requires each checked bag to be less than 35 x 30 x 17 inches (90 x 75 x 43 cm).
Carry-on luggage is never measured in linear dimensions, as each bag must fit within the compact overhead locker. Although the most common carry-on size limit is 56 x 36 x 23 cm (22 x 14 x 9 inches), many airlines stray from the norm. Again, check your airline’s website before leaving for the airport.
The rule of thumb for a personal item is it must fit entirely under your seat. That said, not all aircraft seats are the same size, and many airlines set strict size limits. The most common maximum personal item dimensions are 45 x 35 x 20 cm (18 x 14 x 8 inches), though these can differ between airlines.
If you can’t find the details in your booking confirmation email, search for size restrictions on the relevant airline’s webpage.