Bringing favorite toiletries on a trip can help to avoid the low-quality products found in hotel rooms, but travelers are governed by some serious airport restrictions. Put personal items in checked luggage for convenience, but if you need to pack toiletries in carry-on baggage be sure to follow the rules. All toiletries must meet regulations set by the U.S. Transportation Security Administration (TSA) when departing the U.S. (or the rules of the country in which you're located) to avoid being confiscated at the airport security checkpoint. This is known as the 3-1-1 rule, which mean each traveler can brings toiletries in 3.4 oz bottles or less in one quart-sized plastic bag, with one bag per passenger.

Individual Sizes

For carry-on bags, all liquid toiletries, such as toothpaste and lotion, must be in bottles or packages labeled as containing 3.4 ounces (100 ml) or less of liquid, according to the TSA. Non-liquid toiletries do not have an individual size limitation if they fit inside a carry-on bag. Liquid toiletries exceeding 3.4 ounces can go into checked baggage. Travelers departing from non-U.S. airports should call the airline to check the local regulations, although many follow TSA standards. For example, European Union countries follow the 100 ml limit on liquid toiletries, according to the European Commission.

Total Sizes

U.S. passengers must limit carry-on liquid toiletries to a quart-sized, zip-sealed plastic bag. Outside the U.S., policies will vary. European Union airlines, for example, require passengers to keep liquids in a transparent, resealable 1 liter (1.056 quarts) bag, while Air China doesn't have a bag size requirement. There is typically no limit on the number of toiletries put in your checked baggage, but airlines often have company-specific size and weight limitations for carry-on bags and checked luggage.

Deodorant and Makeup

Stick and crystal deodorants do not have to abide by size limitations for liquid products, reports the TSA, but spray and wet deodorants do. Liquid-based makeup, such as mascara or concealer, is also governed by the 3.4-ounce rule for carry-on bags. Powders and solid makeup, such as eyeshadow or eyeliner pencils, have no size limitations.

Aerosols

Aerosol toiletries such as hairspray or mousse are exempt from the TSA's ban on aerosol products in carry-on and checked baggage. The TSA notes that passengers can bring such products on a plane in "limited quantities," but an exact number is undefined. Travelers are probably safe with a couple of cans, but a suitcase full of hairspray will catch the TSA's attention. Be mindful when packing and try to limit the amount of aerosols.