The snack offerings and flight attendant uniforms vary, but most American airlines are on roughly the same page when it comes to carry-on allowances. International airlines, on the other hand, have a huge range of policies. Some allow carry-ons that weigh no more than 15 pounds; others allow carry-ons weighing up to 50 pounds. Before heading off for a flight, investigate the international airline's current guidelines.

What Should I Know About International Carry-ons?

There is no universal maximum size for carry-ons, also called hand luggage in some places, including the U.K. Each airline provides its own maximum measurements and/or maximum weight for these items. Like with domestic airlines, there's often a lot of variation within one company's allowances. For companies like British Airways, which has several subsidiaries and partnerships with other smaller airlines, baggage allowances can vary from airline to airline. Passengers in higher ticket classes like first or business are often allowed to bring more baggage into the cabin than passengers in economy class, so it's important to check your ticket type when packing for a trip.

Carry-on allowances can also vary depending on the country you're flying into or out of. Specifically, flights that travel to or from Brazil and India tend to have slightly different carry-on policies than other flights.

What Are the Normal Carry-on Allowances for International Flights?

Many international airlines, like most domestic airlines, allow economy passengers to bring one suitcase or other large bag into the cabin, plus one personal item such as a purse, backpack or laptop bag. Air Canada has carry-on allowances similar to those of U.S. airlines, for example. It allows each passenger to carry on a bag up to 21.5 by 15.5 by 9 inches in size, plus a personal item measuring up to 17 by 13 by 6 inches. British Airways has similar policies, allowing carry-ons measuring up to 22 by 18 by 10 inches and personal items measuring up to 16 by 12 by 6 inches in size. One quirk of British Airways' policies is that it accepts much heavier carry-ons than other airlines. Each bag can weigh up to 51 pounds.

Many international airlines are much stricter about carry-on weight. Passengers on Virgin Australia are limited to no more than 7 kilograms (15 pounds) of carry-on luggage, which can take the form of two small bags or one small bag plus a garment bag. The carrier also allows each passenger to bring one personal item on board, which can be a purse or laptop bag.

By contrast, Emirates does not allow economy passengers to bring two items. Passengers traveling in economy class may only carry one piece of carry-on luggage, weighing up to 15 pounds and measuring no more than 22 by 15 by 8 inches. Travelers in first or business class are allowed two carry-ons, except on flights departing from India; all passengers are limited to a single carry-on. For flights leaving from Brazil, carry-ons can weigh up to 22 pounds.

One more complication: Airlines change their carry-on policies frequently. Like United did when it introduced a basic economy fare that doesn't include a free carry-on, international airlines often roll out new ticket classes and policies designed to save money. Check with the airline for its current carry-on restrictions before traveling.