The 3.4-ounce limit for liquids in carry-on bags

The 3.4-ounce (100 milliliter) limit applies to most liquids, gels, creams, and pastes you bring through airport security in your carry-on bag. This is a Transportation Security Administration (TSA) rule that applies to flights departing from U.S. airports. Each container must be 3.4 ounces or smaller — a 3.5-ounce bottle will not pass through security, even if it is mostly empty.

The rule exists because the TSA classifies certain liquids as potential security risks. The limit is not about weight; it is about the volume of the container itself. A full 3.4-ounce bottle and an empty 3.4-ounce bottle are treated the same way at security.

All your liquid containers must fit inside a single quart-sized clear plastic bag. You remove this bag from your carry-on at the security checkpoint and place it in a bin. If your liquids do not fit in one quart-sized bag, you have too much.

Key Takeaways

  • Each liquid container in your carry-on must be 3.4 ounces (100 milliliters) or smaller, and all containers together must fit in one quart-sized clear plastic bag.
  • Liquids include shampoo, conditioner, lotion, toothpaste, peanut butter, yogurt, honey, and other thick substances — not just thin liquids.
  • You can pack larger bottles of liquids in checked luggage with no size limit, though some airlines restrict hazardous materials.
  • The TSA provides free quart-sized bags at security checkpoints if you do not have one, but bringing your own saves time.
  • International flights may have different rules depending on the country of origin and destination, so check with your airline before traveling.

What counts as a liquid under TSA rules

The TSA defines liquids broadly. Beyond water and juice, the category includes shampoo, conditioner, body lotion, face cream, sunscreen, deodorant (stick deodorant is allowed; gel or spray is not), toothpaste, mouthwash, and perfume. Thick or spreadable items like peanut butter, jam, honey, yogurt, and hummus also count as liquids for TSA purposes.

Solid items do not count. A bar of soap, a stick of deodorant, a solid perfume, or a jar of lip balm can go in your carry-on in any quantity. If you are unsure whether something is a liquid or a solid, the TSA website has a searchable "What Can I Bring?" tool where you can type in the specific item.

Medications and medical equipment have different rules. Liquid medications in reasonable quantities for your trip do not have to follow the 3.4-ounce limit, but you should carry them in their original labeled containers and be prepared to explain them to security. Insulin, for example, can exceed 3.4 ounces.

How to pack liquids in your carry-on

Start by gathering all your liquid containers and measuring each one. If any bottle or jar is larger than 3.4 ounces, move it to your checked bag instead. Decant larger products into smaller containers if you want to bring them — travel-sized bottles are widely available at drugstores and online.

Place all your 3.4-ounce-or-smaller containers into a clear quart-sized plastic bag. The bag must be clear so security can see inside without opening it. Seal the bag completely. The TSA provides these bags free at security checkpoints, but you can also bring your own or purchase them ahead of time.

Pack the sealed bag where you can reach it easily — near the top of your carry-on or in an outside pocket. At the security checkpoint, you will remove the bag and place it in a bin on the X-ray conveyor belt. After you pass through security, you can put it back in your carry-on.

Packing liquids in checked luggage instead

Checked bags have no size limit for liquids. You can pack full-sized bottles of shampoo, lotion, sunscreen, and other liquids in your checked luggage without restriction. This is the best option if you want to bring your regular-sized products and do not want to buy travel sizes.

Some airlines restrict hazardous materials in checked bags — flammable items like lighter fluid, paint thinner, or certain aerosols may not be allowed at all. Check your airline's baggage policy before packing. Most common toiletries and food items are fine in checked bags.

Keep in mind that checked bags can be delayed or lost. If you need a liquid item during your flight or when ready upon arrival, pack a small amount in your carry-on within the 3.4-ounce limit.

Rules for international travel

The 3.4-ounce rule applies to flights departing from U.S. airports, but rules vary by country. If you are flying from a European airport, Canada, Australia, or another country, that country's aviation authority sets the rules. Many countries follow the same 3.4-ounce limit, but some do not.

If your flight includes a connection in another country, you may need to repack your liquids. For example, if you fly from the U.S. to Europe and then to another country, you might pass through security twice. Research the rules for each country on your itinerary.

Your airline's website usually lists liquid rules for the countries it serves. If you are unsure, contact the airline directly before your trip.

Common mistakes to avoid at security

The most common mistake is packing a liquid container larger than 3.4 ounces in your carry-on. Security will confiscate it, and you cannot retrieve it after you pass through the checkpoint. Check every container before you leave home.

Another mistake is forgetting to remove your liquids bag from your carry-on at the checkpoint. This slows down the security line. Have your bag ready to pull out as you approach the X-ray machine.

Do not assume a container is empty just because it looks light. A nearly empty 5-ounce bottle will still be rejected. The TSA measures the container size, not the amount of product inside.

Frequently Asked Questions

Can I bring a full-sized deodorant stick in my carry-on?

Yes. Solid deodorant sticks are allowed in unlimited quantities in carry-on bags. Only gel, spray, and liquid deodorants count as liquids and must follow the 3.4-ounce rule.

What if I forget my liquids bag at home?

The TSA provides free quart-sized clear plastic bags at security checkpoints. You can ask an officer for one and pack your liquids into it before going through the scanner. This adds a few minutes to your security wait.

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

Yes. A completely full 3.4-ounce container is allowed. The rule is based on the container size, not how much liquid is inside. An empty 3.4-ounce bottle is also allowed.

Do I need to remove my liquids bag if I have TSA PreCheck?

TSA PreCheck members do not have to remove their liquids bag, shoes, or belt at most U.S. airports. However, the 3.4-ounce limit still applies — you still cannot bring containers larger than 3.4 ounces in your carry-on.

Are there any liquids that are completely banned from carry-on bags?

Yes. Flammable liquids like lighter fluid, paint thinner, and certain aerosols are banned from both carry-on and checked bags. The TSA website lists prohibited items by category. When in doubt, pack questionable items in checked luggage or leave them at home.