The 3.4-ounce rule for carry-on bags

You can bring a container of liquid through TSA security if it holds 3.4 ounces (100 milliliters) or less. This is the size limit for a single container. The rule applies to anything that flows, spreads, or is pourable—including gels, creams, pastes, and aerosols.

The limit exists because TSA screens liquids differently than solid items. A container larger than 3.4 ounces will be stopped at the checkpoint, even if it is mostly empty. You cannot bring a 5-ounce bottle that is only half full.

This rule applies only to carry-on bags. Checked luggage has no ounce limit for most liquids, though some items (like flammable substances) are prohibited in checked bags entirely.

Key Takeaways

  • Each liquid container in your carry-on must be 3.4 ounces or smaller; a single larger bottle will be confiscated even if partially empty.
  • All containers must fit inside a single clear quart-sized plastic bag, and you remove this bag at security.
  • Checked luggage has no ounce limit for liquids, but some substances like lighter fluid are banned from checked bags.
  • Solid items like deodorant sticks, lip balm, and peanut butter are not subject to the liquid rule and can be any size in carry-on bags.
  • TSA officers make the final call on whether an item counts as a liquid; when in doubt, pack it in checked luggage or buy it after security.

What counts as a liquid under the 3.4-ounce rule

TSA defines liquids broadly. The category includes obvious items like water, juice, and shampoo, but also gels (hair gel, aloe vera), creams (moisturizer, sunscreen), pastes (toothpaste, peanut butter), and aerosols (deodorant spray, hairspray). Yogurt, honey, and peanut butter are liquids by this definition, even though you might not think of them that way.

Solid items do not count. A stick of deodorant, a bar of soap, a tube of lip balm, or a jar of solid coconut oil can be any size in your carry-on. The distinction matters because TSA cannot easily screen thick or opaque liquids the way they screen water.

If you are unsure whether something counts, the safest choice is to pack it in your checked bag or buy it after you pass through security. TSA officers have final authority to decide, and their judgment can vary.

How to pack liquids in your carry-on

All your liquid containers must fit inside a single clear quart-sized plastic bag. This is roughly 7 inches by 8 inches. You remove this bag at the security checkpoint and place it in a bin for screening, separate from your other belongings.

Each container inside the bag must be 3.4 ounces or smaller. You can bring multiple small containers—for example, three 3-ounce bottles of shampoo—as long as they all fit in the quart bag and you remove it at security. The quart bag itself is free; TSA does not provide one, so bring your own or ask for one at the checkpoint.

Containers do not need to be full. A 3-ounce container that is half empty still counts as a 3-ounce container and is allowed. What matters is the container size, not how much liquid is inside.

Liquids in checked luggage

Checked bags have no ounce limit for most liquids. You can pack full-size bottles of shampoo, lotion, perfume, or other toiletries in your checked luggage without restriction. This is why many travelers pack larger bottles in checked bags and carry only travel sizes on board.

Some substances are banned from checked luggage entirely, regardless of size. These include flammable items like lighter fluid, paint thinner, and certain cleaning products. Alcohol above 140 proof is also prohibited in checked bags. If you are traveling with something you think might be restricted, check the TSA website or call your airline before you pack.

Items that look like liquids but are not

Solid or semi-solid items bypass the liquid rule. Deodorant sticks, solid perfume, lip balm, solid lotion bars, peanut butter, and jam are all allowed in carry-on bags in any quantity. Cheese, butter, and other spreadable foods that are solid at room temperature are also permitted.

The line between solid and liquid can be fuzzy. Gel deodorant is a liquid; stick deodorant is not. Aerosol deodorant is a liquid. If a product is in a spray bottle or aerosol can, assume it is a liquid and subject to the 3.4-ounce rule.

What happens if you bring a container that is too large

TSA will confiscate any liquid container larger than 3.4 ounces at the security checkpoint. You will not be able to bring it on the plane, and you will not get it back. This happens even if the container is mostly empty or if you did not realize the rule applied to that item.

If you discover you have a large container when you reach security, you have a few options. You can throw it away, leave it with someone outside security, or go back to your car or hotel if you have time. Some airports have mail services where you can mail items to yourself, though this is not common.

The best strategy is to check your carry-on bag before you leave home. Look for anything pourable, spreadable, or in a spray bottle, and either move it to checked luggage or buy a travel-size version.

International flights and different rules

The 3.4-ounce rule applies to flights departing from the United States. If you are flying internationally, the country you are flying to may have different rules. Some countries use the same 100-milliliter limit; others are stricter or more lenient.

If you are connecting through a non-U.S. airport, you may need to repack your liquids or move them to checked luggage. When you land in another country and check in for a connecting flight, that country's security rules explore. Research your destination's rules before you pack, or plan to buy liquids after you land.

Frequently Asked Questions

Can I bring a 3.4-ounce bottle that is completely full?

Yes. The limit is 3.4 ounces per container, and a full 3.4-ounce bottle is allowed. It must fit in your quart-sized bag along with any other liquids you are bringing.

What if my toothpaste tube says 4 ounces but is mostly empty?

TSA will stop it at security. The rule is based on container size, not how much product is inside. A 4-ounce tube is over the limit, even if it is half squeezed out. Buy a travel-size tube or pack it in checked luggage.

Do I need to remove the quart bag from my carry-on at every checkpoint?

Yes. At U.S. security checkpoints, you must remove your liquids bag and place it in a bin for X-ray screening, just like you remove shoes and electronics. This is standard procedure at every airport.

Can I bring an empty water bottle through security and fill it at a fountain?

Yes. An empty bottle is not a liquid and is not subject to the 3.4-ounce rule. You can bring an empty reusable bottle through security and fill it at a water fountain or refill station after you pass the checkpoint.

Are frozen liquids allowed in carry-on bags?

Frozen liquids are treated as solids if they are completely solid when you go through security. Ice is allowed. However, if a frozen item begins to thaw and becomes liquid during your flight, TSA considers it a liquid. To be safe, pack frozen items in checked luggage.