If you’re anticipating an upcoming international vacation or business trip, you may momentarily forget air travel restrictions that cover what is and isn’t allowed in carry-on and checked luggage. Yet contravening these regulations can mean frustration and delay or, even the worst-case scenario, a missed flight. Follow TSA and U.S. Customs and Border Protection guidelines closely when packing for international flights. The Liquids Rule applies to carry-on luggage on all flights, and customs duty restrictions apply to passengers arriving in the United States from another country.

Carry-on Luggage Restrictions

Carry-on luggage mustn’t be too large or contain restricted items. The maximum dimensions for carry-on baggage are 22 x 18 x 10 inches, although airlines can impose their own rules on the size and number of carry-on bags they allow. One of the most crucial regulations that applies to the contents of carry-on luggage, the Liquids Rule, also applies to creams, pastes, gels and aerosols. Containers holding these substances in carry-on bags must not be larger than 3.4 ounces. Place all the containers in a clear, resealable 1-quart bag for inspection by the TSA. Complex regulations apply to other carry-on luggage items such as food, medicines, batteries and sharp objects. For example, disposable razors are allowed, but corkscrews or not. Contact the TSA for detailed advice on what you can pack in carry-on bags.

Checked Luggage for International Flights

Weight and size restrictions apply to checked luggage on international flights. For the safety of baggage handlers, luggage shouldn’t weigh more than 50 pounds. Airport workers run the risk of injury from lifting heavy luggage, and in the U.S. and European Union, the maximum weight for an item of checked luggage is 70 pounds. However, airlines can impose lower weight restrictions. Many airlines allow passengers two pieces of checked baggage, and the added total dimensions of each piece cannot be more than 62 inches. Again, airlines have discretion over checked luggage regulations, so read the information on your ticket or contact the airline for guidance before traveling. Liquids in containers larger than 3.4 ounces and many other regular items are allowed in checked luggage. Contact the TSA for detailed guidance.

Duty-Free Allowances

When returning from another country, airline passengers can take advantage of duty-free allowances. “Duty” is a tax that is due on merchandise that passengers purchase abroad and bring into the U.S., but items up to a certain total value are duty-free, which means that no tax is due. The total value of duty-free items allowed per passenger is between $200 and $1,600, depending on the country the returning flight departed from. Adults over the age of 21 can bring in up to 33.8 fluid ounces of alcohol duty-free, providing the local state laws allow it. Up to 200 cigarettes or 100 cigars are also allowed. If the value of merchandise exceeds the duty-free allowance or if the passenger used part of the allowance in the previous 30 days, duty tax is due, so it’s worth checking with U.S. Customs and Border Control if in doubt.