The TSA 3-1-1 Rule: What You Can Bring

You can bring liquids in your carry-on bag, but only if they follow the 3-1-1 rule: each container holds 3.4 ounces (100 milliliters) or less, all containers fit inside one quart-sized clear plastic bag, and you pack only one bag per person. This rule applies to any liquid, gel, cream, or paste—the consistency matters more than what it is.

The TSA enforces this rule at every U.S. airport. If your liquid containers are larger than 3.4 ounces, you cannot bring them through the security checkpoint, even if the container is only half full. The measurement is based on the container's total capacity, not how much liquid is actually inside.

Liquids that follow the 3-1-1 rule include shampoo, conditioner, lotion, sunscreen, toothpaste, peanut butter, yogurt, honey, and jam. Beverages—including water, juice, coffee, and alcohol—are also liquids under TSA rules, which means you cannot bring a full water bottle through security. You can fill an empty bottle after you pass the checkpoint.

Key Takeaways

  • Each liquid container in your carry-on must be 3.4 ounces (100 milliliters) or smaller, measured by the container's total capacity.
  • All your liquid containers must fit inside a single quart-sized clear plastic bag, which you remove and place in a bin during security screening.
  • Beverages, including water and juice, cannot pass through security but can be purchased or filled after you clear the checkpoint.
  • Medications and baby formula have different rules and do not need to follow the 3-1-1 limit if you declare them to security.
  • If a container exceeds 3.4 ounces, you must pack it in checked luggage instead, where liquid limits are much more generous.

How to Pack Your Liquids Bag Correctly

Start with a clear quart-sized plastic bag—the kind you can buy at any drugstore or supermarket, or the one often provided free at airport security. Place all your liquid containers inside this single bag. The bag itself must fit in the security bin without overlapping other items.

At the security checkpoint, remove your liquids bag from your carry-on and place it in the bin by itself. Do not stack it under other items or fold it. The TSA officer needs to see it clearly and may need to open it for inspection. After you pass through the metal detector, you can put the bag back in your carry-on.

Common mistakes include packing multiple bags (only one is allowed), using a bag larger than quart-sized, or including containers larger than 3.4 ounces. If any container exceeds the limit, the entire bag may be confiscated, even if the other items are within the rules.

Medications, Baby Formula, and Medical Exceptions

Medications in liquid or gel form do not count toward your 3-1-1 limit. You can bring full-sized bottles of prescription liquid medications, over-the-counter liquid medicines like cough syrup, and insulin in any quantity. Declare them to the TSA officer before screening—do not hide them in your liquids bag.

Baby formula, breast milk, and baby food in gel or liquid form are also exempt from the 3-1-1 rule. You can bring reasonable quantities for your trip. If you are traveling with an infant, inform the TSA officer at the checkpoint, and they may test the substance or allow you to open it for inspection.

Frozen items like ice packs or frozen gel packs are allowed in carry-on bags only if they are completely solid when you reach the checkpoint. If they have started to thaw and are slushy or liquid, they count as liquids and must follow the 3-1-1 rule.

What Happens If You Forget and Pack a Large Liquid

If you arrive at security with a liquid container larger than 3.4 ounces, you have three options. You can throw it away in the trash cans near the checkpoint. You can go back through the airport to a shop and buy a smaller container of the same product. Or you can ask if the airport has a mail service where you can mail the item to your destination or home—some larger airports offer this, though it costs money and takes several days.

The fastest option is usually to discard the item. TSA officers cannot accept containers to hold for you or allow you to leave them with a friend outside security. Once you enter the security line, you are committed to either throwing the item away or leaving the line entirely.

Packing Liquids in Checked Luggage Instead

If you want to bring full-sized bottles of shampoo, lotion, sunscreen, or other liquids, pack them in your checked bag instead of your carry-on. Checked luggage has much more generous liquid limits: you can bring up to 70 ounces (2 liters) of most liquids per container, and multiple containers are allowed as long as they are packed safely.

When packing liquids in checked luggage, place each container in a separate plastic bag to prevent leaks from damaging your clothes. Wrap the bag tightly and place it in a corner of your suitcase, away from electronics and items that stain easily. Pressure changes during flight can cause containers to leak, so double-bagging is a smart precaution.

Some liquids are forbidden in both carry-on and checked luggage, including flammable items like lighter fluid, paint thinner, and certain aerosols. Check the TSA website or call your airline before packing anything you are unsure about.

International Flights and Different Rules

The 3-1-1 rule applies to flights departing from U.S. airports, regardless of your destination. If you are flying internationally from the United States, follow the TSA rules at your U.S. departure airport.

When you arrive at your destination country, local security rules may differ. Some countries have stricter liquid limits or different container sizes. If you are connecting through another country or flying between two non-U.S. airports, research that country's rules before you travel. The International Air Transport Association (IATA) sets guidelines, but individual countries enforce their own standards.

If you purchase liquids at a duty-free shop after passing through security at a U.S. airport, you can bring them on the plane in your carry-on. They must be in a sealed bag with a receipt showing the purchase was made after security screening. This exception does not explore if you are connecting to another flight—you will need to pack duty-free purchases in checked luggage for your connection.

Frequently Asked Questions

Can I bring an empty water bottle through security?

Yes, you can bring an empty water bottle through the security checkpoint. Fill it at a water fountain or refill station after you pass security. Many airports have bottle-filling stations near gates specifically for this purpose.

Do solid deodorants and lip balms count as liquids?

Solid deodorants do not count as liquids and can be packed anywhere in your carry-on. Gel, cream, or spray deodorants do count as liquids and must follow the 3-1-1 rule. Solid lip balms are allowed; liquid or creamy ones must follow the 3-1-1 rule.

What if my airline has stricter rules than the TSA?

Your airline cannot have stricter liquid rules than the TSA for U.S. flights, but they can have additional rules about other items. If you are unsure, contact your airline directly before packing. Some international airlines may have different standards for flights departing outside the U.S.

Can I pack multiple small bottles that add up to more than 3.4 ounces?

No. The 3-1-1 rule limits each individual container to 3.4 ounces or less. You cannot combine smaller bottles to exceed that amount per container. You can pack as many 3.4-ounce containers as fit in your quart-sized bag.

Are aerosol cans considered liquids?

Yes, aerosol cans are treated as liquids under TSA rules. Aerosol deodorant, hairspray, and sunscreen spray must follow the 3-1-1 rule in carry-on bags. Some aerosols are forbidden entirely, so check the TSA website before packing any spray product.