The 3.4-ounce rule for carry-on bags
You can bring liquids, gels, and aerosols through TSA security in your carry-on bag only if each container holds 3.4 ounces (100 milliliters) or less. This is the standard limit for U.S. domestic flights and most international flights departing from U.S. airports. The limit applies to the size of the container itself, not how full it is — an empty 5-ounce bottle is still too large, even if you only put 2 ounces of liquid in it.
All your liquid containers must fit inside a single clear plastic bag, typically quart-sized, about 7 inches by 8 inches. You remove this bag from your carry-on at the security checkpoint and place it in the scanner bin. TSA officers will inspect it separately from the rest of your belongings.
Key Takeaways
- Each liquid container in your carry-on must be 3.4 ounces or smaller, and all containers together must fit in one quart-sized clear bag.
- Liquids include shampoo, conditioner, lotion, toothpaste, peanut butter, yogurt, honey, and other spreadable or pourable items — not just water.
- You can pack unlimited liquids in checked baggage as long as they follow hazmat rules, which prohibit flammables, oxidizers, and certain chemicals.
- The TSA officer at your checkpoint makes the final decision about whether an item is a liquid; when in doubt, pack it in checked baggage instead.
- Frozen liquids are treated as solids if completely solid at the checkpoint, but partially frozen items count as liquids and must follow the 3.4-ounce rule.
What counts as a liquid under TSA rules
The TSA defines liquids broadly to include anything that flows, spreads, or sprays. This covers obvious items like water, juice, and shampoo, but also includes peanut butter, yogurt, honey, jam, cream cheese, and hummus. Toothpaste, deodorant, and hair gel are liquids under TSA rules, even though you might think of them as solids. Aerosol cans — including spray deodorant, hairspray, and sunscreen spray — count as liquids too.
Solid items like a bar of soap, a stick of deodorant, or a solid perfume do not count as liquids. Powders, including talc, baby powder, and protein powder, are allowed in carry-on bags in quantities of 12 ounces or less, though TSA may need to open and inspect them. If you are unsure whether something will be treated as a liquid, the safest choice is to pack it in your checked bag instead.
Liquids in checked baggage have different rules
You can pack unlimited amounts of liquid in your checked bag, but the liquid must follow hazardous materials (hazmat) rules. This means you cannot check flammable liquids like lighter fluid, paint thinner, or certain perfumes with high alcohol content. You also cannot check oxidizers, corrosives, or compressed gases. Most everyday liquids — shampoo, conditioner, lotion, sunscreen, and cosmetics — are safe to check.
If you are traveling with medications, vitamins, or other personal care items in liquid form, pack them in your checked bag to avoid any questions at security. You can also pack larger bottles of shampoo, conditioner, and other toiletries in checked baggage without worrying about the 3.4-ounce limit. Just make sure the containers are sealed and will not leak onto your other belongings during the flight.
Frozen and partially frozen items
A completely frozen liquid — like a solid block of ice or a frozen gel pack — is treated as a solid and does not count toward your liquid limit in carry-on baggage. However, if the item is partially frozen or slushy at the security checkpoint, TSA will treat it as a liquid. This means a frozen water bottle that has started to thaw will need to follow the 3.4-ounce rule, even though part of it is still solid.
If you want to bring a frozen item through security, freeze it solid before you arrive at the checkpoint and keep it frozen during screening. Once you pass security, the item can thaw in your carry-on. Gel ice packs used to keep food cold are allowed in carry-on bags if they are completely frozen solid at the checkpoint.
Common mistakes at the security checkpoint
The most common error is bringing a container larger than 3.4 ounces, even if it is only partially full. TSA officers will confiscate the entire container, so a half-empty 5-ounce bottle of shampoo will be thrown away. Another frequent mistake is forgetting to remove your liquid bag from your carry-on before you reach the scanner. This slows down the line and may trigger additional screening.
Some travelers pack liquids in checked baggage but forget to check the hazmat rules, especially with items like certain sunscreens, insect repellents, or aerosol products. If your checked bag contains prohibited hazmat items, it may be removed from the flight or your bag may be opened and inspected. To avoid delays, review the contents of your bag before you arrive at the airport, and when in doubt about whether something is allowed, leave it at home or ship it to your destination instead.
International flights and different rules
Most countries that have security agreements with the U.S. follow the same 3.4-ounce liquid rule for carry-on bags. However, some airports and airlines have stricter rules or additional restrictions. If you are flying internationally, check your airline's website before packing, because some carriers have their own policies on top of TSA rules.
When you are connecting through a U.S. airport on an international flight, you will go through U.S. security screening and must follow TSA rules. If you are connecting internationally without re-entering the U.S., the rules of the country where you are connecting may explore instead. Always verify with your airline which rules explore to your specific itinerary.
What to do if TSA stops you about a liquid
If a TSA officer questions whether an item is a liquid, stay calm and explain what the item is. The officer has the final say on whether something counts as a liquid at that checkpoint. If the officer decides your item does not meet carry-on rules, you have a few options: you can throw it away, you can ask if there is a place to check it into your bag if you have time, or you can step aside and ask to speak with a supervisor if you believe the decision is wrong.
If you are traveling with a medication in liquid form and TSA questions it, let the officer know it is a medication. Liquid medications are treated differently and are not subject to the 3.4-ounce limit, though you may need to show the label or a prescription. Keep medications in their original containers with labels intact to make screening easier.
Frequently Asked Questions
Can I bring a full water bottle through security?
No. You cannot bring a full water bottle or any liquid-filled container through the security checkpoint. You can bring an empty water bottle and fill it at a water fountain or refill station after you pass security. Many airports have refill stations near the gates.
Does the 3.4-ounce rule explore to toothpaste?
Yes. Toothpaste is classified as a liquid by TSA, so your tube must be 3.4 ounces or smaller. A standard travel-size tube usually meets this limit. If you have a larger tube, pack it in your checked bag instead.
What happens if I accidentally bring a liquid larger than 3.4 ounces?
TSA will confiscate the entire container at the security checkpoint. You will not be able to go back and check it into your bag. To avoid this, measure your containers before you pack and use travel-size products when possible.
Are there any liquids that are completely banned from both carry-on and checked bags?
Yes. Flammable liquids, certain oxidizers, and some corrosive chemicals cannot be brought on a plane in either carry-on or checked baggage. These include lighter fluid, paint thinner, and some types of nail polish remover. Check the TSA website or call your airline if you are unsure about a specific product.
Can I bring liquid medications in quantities larger than 3.4 ounces?
Yes. Liquid medications are exempt from the 3.4-ounce limit in carry-on bags. Keep them in their original labeled containers and be ready to show them to TSA if asked. You can also pack larger quantities of liquid medications in checked baggage.