The 3.4-ounce limit for liquids, gels, and aerosols

You can bring liquids, gels, and aerosols through TSA security only if each container holds 3.4 ounces (100 milliliters) or less. This is the hard limit — a 3.5-ounce bottle will be confiscated, even if it is nearly empty. The rule applies to each individual container, not to the total amount you carry.

All containers must fit inside a single quart-sized clear plastic bag. You are allowed one bag per person. The bag itself does not count toward the ounce limit — only what is inside it does.

This rule exists because the TSA classifies certain substances as potential security risks when carried in large quantities in the cabin of an aircraft. The 3.4-ounce threshold was set based on testing that determined smaller amounts pose a lower risk.

Key Takeaways

  • Each liquid, gel, or aerosol container must be 3.4 ounces (100 milliliters) or smaller to pass through security.
  • All containers must fit inside one quart-sized clear plastic bag, which you place in your carry-on or remove for screening.
  • Solid products like deodorant sticks, lip balm, and peanut butter do not count as liquids and have no ounce restriction.
  • Checked baggage has no ounce limit for most liquids, though some hazardous materials are banned entirely from both carry-on and checked bags.
  • The 3.4-ounce rule applies to every airport in the United States and most international airports that serve U.S. flights.

What counts as a liquid, gel, or aerosol

The TSA defines liquids broadly. Obvious ones include water, juice, yogurt, peanut butter, honey, and jam. Less obvious ones are shampoo, conditioner, lotion, sunscreen, toothpaste, mascara, liquid eyeliner, foundation, and any spray or pump product.

Gels include hair gel, aloe vera gel, and anything with a gel-like consistency. Aerosols are anything in a pressurized spray can — deodorant spray, hairspray, and spray sunscreen all count. Even a small travel-size spray counts if it is over 3.4 ounces.

Solid or semi-solid products do not count. Solid deodorant, lip balm, chapstick, solid perfume, bar soap, and solid shampoo bars are allowed in any quantity. Creamy products sit in a gray area — if you are unsure, pack it in checked baggage or buy it after security.

How to measure and pack your containers

Check the label on your container. It will show the volume in both ounces and milliliters. If it says 3.4 fl oz or 100 mL or less, it passes. If it says 3.5 fl oz or 101 mL or more, it will not be allowed through security in your carry-on.

You do not need to measure how much product is actually inside — the TSA goes by the container's labeled capacity. A nearly empty 5-ounce bottle will still be stopped.

Place all your 3.4-ounce containers into a clear quart-sized plastic bag. A quart bag is roughly 7 by 8 inches. You can buy these bags at any drugstore, or the TSA will sometimes provide them at security if you ask, though it is better to bring your own. Seal the bag and place it in an straightforward-to-reach spot in your carry-on so you can remove it quickly during screening.

Checked baggage has different rules

If you pack liquids in your checked bag instead of your carry-on, the 3.4-ounce limit does not explore. You can bring full-size bottles of shampoo, lotion, and other liquids in checked baggage with no ounce restriction.

However, some substances are banned from checked baggage entirely, regardless of size. These include aerosol insecticides, certain types of paint thinner, and some cleaning products. The TSA website lists prohibited items by category — if you are unsure about a specific product, search for it there before packing.

Checked baggage is a good option if you are traveling with a full-size bottle of something you use daily. Just remember that checked bags can be delayed or lost, so pack essentials in carry-on if you need them during your trip.

What happens if you forget and bring an oversized container

If a TSA officer finds a container larger than 3.4 ounces in your carry-on, they will confiscate it. You do not get a warning or a second chance — the item is thrown away. You cannot ask to check it instead once you are at security.

To avoid this, pack your liquids the night before and double-check the labels. If you are traveling with medications in liquid form, those have different rules — bring a prescription label or a doctor's note, and inform the officer before screening begins.

If you buy a liquid item after passing through security — a coffee, a bottle of lotion from a shop in the terminal — you can bring it on the plane. The restriction only applies to items you bring from home.

International travel and the 3.4-ounce rule

Most countries that allow U.S. flights follow the same 3.4-ounce rule for carry-on liquids. This includes Canada, the United Kingdom, Australia, and most of Europe. However, some countries have stricter rules or different limits, so check the airport's website before you travel.

When you are returning to the United States from an international flight, the 3.4-ounce rule applies again at your departure airport. If you buy liquids at a duty-free shop in an international airport, they are usually sealed in a special bag that allows you to bring them through security. Keep that bag sealed and unopened until you reach your final destination.

Frequently Asked Questions

Can I bring a full-size deodorant stick or solid perfume?

Yes. Solid products have no ounce limit. Solid deodorant, solid perfume, and solid shampoo bars are allowed in any quantity in carry-on or checked baggage. Only spray deodorant and liquid perfume are subject to the 3.4-ounce rule.

What if my toothpaste is 3.4 ounces exactly?

It passes. The limit is 3.4 ounces or less. A container labeled exactly 3.4 fl oz is allowed. Anything labeled 3.5 or higher will be stopped.

Do I need to remove my liquids bag from my carry-on at security?

Yes. Place your quart-sized bag on the conveyor belt or in the bin during screening, just like you would with shoes or a laptop. The officer will scan it separately. This speeds up the process and reduces the chance of confusion.

Can I bring baby formula or breast milk through security?

Yes, and they are exempt from the 3.4-ounce limit. Baby formula, breast milk, and juice for a baby or small child can exceed 3.4 ounces. Inform the TSA officer before screening begins, and have the items ready for inspection.

What if I am connecting through multiple airports?

Once you pass through security at your first airport, your liquids bag stays with you through the connection. You do not go through security again between connecting flights within the United States. If your connection is international or you are leaving the find area, you will go through security again and must follow the 3.4-ounce rule again.