How to Pack Toiletries for a Flight: Carry-On Guide

For a flight departing the United States, the carry-on rule is simple: each liquid, gel, aerosol, cream or paste must be in a container of 3.4 fluid ounces (100 milliliters) or less. Put those containers in one clear, quart-sized resealable bag, and bring one bag per passenger. At the security checkpoint, take the bag out of your carry-on and place it in a bin. Anything larger belongs in checked luggage, subject to your airline's rules. The limit applies to the size of the container, not how much is left inside it.

A few minutes of prep prevents most checkpoint problems. Do this before you start filling bottles.

• Check the rules for every airport on your route, not just the departure airport. The US 3-1-1 rule is a good baseline, but some countries and airports have different bag sizes or screening procedures.
• Decide whether you are traveling carry-on only. If you are checking a bag, you can take larger containers, but you also take on more leak risk and the chance that the bag is delayed.
• Read your airline's baggage rules for liquids, aerosols and medications. Airline rules can be stricter than security rules.
• Set out every toiletry you plan to use and split it into two piles: liquids and solids.
• Gather a clear quart-sized resealable bag, small refillable containers, a leakproof toiletry bag and labels. A small funnel helps with decanting.
• Check the weather and trip length. Sunscreen, insect repellent and heavy hair products take up more space than most people expect.

Security officers do not just look for bottles of water. The US Transportation Security Administration treats liquids, gels, aerosols, creams and pastes as liquids for the 3-1-1 rule. That includes toothpaste, lotion, sunscreen, liquid foundation, mascara, lip gloss, hair gel, shaving cream, perfume and aerosol deodorant. Solid stick deodorant, bar soap, loose powder and a dry toothbrush do not count.

The bag is for your carry-on. In a checked bag, you can pack larger bottles, but the airline may still limit quantity or prohibit certain items. Checked bags also face pressure changes and rough handling, so a bottle that survives the outbound flight can still leak on the return trip.

• Packing a full-size bottle with a little left. The container is still over the limit. Fix: transfer the product to a smaller bottle or check the bag.
• Filling bottles to the brim. Pressure changes can force liquid out around the cap. Fix: leave about a quarter of the bottle empty and close the cap tightly.
• Using a bag that is too small. A sandwich bag is not a quart bag, and an overstuffed quart bag may not seal. Fix: use one clear quart-sized bag and remove nonessentials.
• Burying the bag in the carry-on. You will have to unpack at security. Fix: put it in an exterior pocket or on top.
• Forgetting that creams and pastes count. Toothpaste, sunscreen and foundation are liquids for screening. Fix: sort by texture, not by what the label calls the product.
• Packing aerosols in the cabin. Most full-size cans exceed the limit and some are flammable. Fix: check the size and airline rules, or plan to buy the product at your destination.
• Putting essential medication in a checked bag. A delayed bag can separate you from medication. Fix: keep medication in your carry-on in its labeled container.

• Medically necessary liquids. Prescription medicine, contact lens solution and similar items may be allowed in larger amounts, but you must tell the security officer. Keep them in original labeled packaging and pack them in carry-on.
• One bag per passenger. The quart bag allowance is per person, not per family. If you are traveling with children, each passenger gets a bag, but the contents still have to fit the rules.
• International departures. The 3-1-1 rule is a US rule. Other countries may use 100 ml containers but require a different bag size or screening method. Check the airport you are departing from, not just your destination.
• Flammable aerosols and alcohol. Some hairsprays, dry shampoos and sanitizers are flammable or alcohol-based. Check the airline's dangerous goods rules and never puncture or heat a pressurized can.
• Razors and sharp items. Disposable razors are generally allowed in carry-on, but straight razors and loose blades may not be. Check the current rules if you are unsure.
• Hand sanitizer. It is a liquid. Keep it within the carry-on limit unless the airport's current rules say otherwise, and pack it in the quart bag.

The exact contents depend on your trip, but a simple kit for a week of carry-on travel looks like this:

• Toothbrush and a travel-size toothpaste (3.4 oz or less)
• Solid deodorant or a travel-size gel deodorant
• Bar soap or a small body wash; bar shampoo and conditioner if you prefer solids
• Travel-size sunscreen and lip balm with SPF
• Small shampoo, conditioner and lotion only if you are not relying on hotel supplies
• Razor, comb, hair ties and a small amount of styling product
• Essential medication in a labeled container, plus contact lens solution if it is medically necessary

Lay the containers flat in the clear bag, then put the bag in the toiletry case. If the bag will not close easily, you have packed too much. A good test is to close the bag, hold it by the zipper and give it a gentle shake. Nothing should slide out or press hard against the seal.