The 3.4 fl oz limit for liquids in carry-on bags

TSA allows liquids, gels, and aerosols in your carry-on bag only if each container holds 3.4 fluid ounces (100 milliliters) or less. This is the hard limit — a 3.5 fl oz bottle will not pass through security, even if it is mostly empty. The rule applies to the container size, not how much liquid is actually inside.

This limit exists because of aviation security rules set by the Department of Homeland Security. The thinking is that smaller quantities of liquid pose less risk during flight. You can bring multiple 3.4 fl oz containers, as long as they all fit inside a single clear plastic bag (usually a quart-sized freezer bag) and you remove that bag from your carry-on at the security checkpoint.

Checked baggage has no fluid ounce limit for most liquids, though some items like alcohol, paint, and certain chemicals have their own restrictions based on hazardous materials rules. If you are traveling with larger bottles, pack them in checked luggage instead.

Key Takeaways

  • Each liquid container in your carry-on must be 3.4 fl oz (100 ml) or smaller; the container size is what matters, not how full it is.
  • All liquids, gels, and aerosols in carry-on bags must fit inside one clear quart-sized plastic bag, which you remove at security.
  • You can bring unlimited liquids in checked baggage, though hazardous materials like alcohol and paint have separate rules.
  • Common items that count toward the liquid limit include shampoo, conditioner, lotion, toothpaste, deodorant, and sunscreen.
  • Solid items like deodorant sticks, lip balm, and peanut butter do not count as liquids and can travel in carry-on without size limits.

What counts as a liquid under TSA rules

The TSA definition of liquid is broader than you might expect. It includes anything that flows, spreads, or sprays: shampoo, conditioner, body lotion, face cream, sunscreen, toothpaste, deodorant spray, hairspray, perfume, cologne, and liquid eyeliner all count. Peanut butter, honey, jam, and yogurt also count because they are spreadable. Mascara and liquid foundation count too.

Solid or semi-solid items do not count. Deodorant sticks, lip balm, solid perfume, bar soap, and solid shampoo bars are fine in any quantity in your carry-on. Creamy items sit in a gray area — if TSA agents at your specific airport consider it a gel, it must follow the 3.4 fl oz rule. When in doubt, pack cream-based products in checked luggage or buy travel sizes.

Gels and aerosols follow the same 3.4 fl oz limit as liquids. This includes hair gel, aloe vera gel, shaving cream, whipped sunscreen, and anything in a spray can. The container itself must be 3.4 fl oz or smaller.

How to pack liquids for carry-on travel

Start by collecting all your liquid containers and checking the size printed on each one. If a bottle says 5 fl oz, it exceeds the limit — you cannot bring it in carry-on, even if you pour some out. Buy travel-size versions instead, or pack full-size bottles in your checked bag.

Once you have confirmed all containers are 3.4 fl oz or smaller, place them inside a single clear plastic bag. A quart-sized freezer bag (roughly 7 inches by 8 inches) is the standard size TSA expects. Seal it closed. At the security checkpoint, remove this bag from your carry-on and place it in the bin with your shoes and electronics — do not leave it in your bag.

TSA agents will scan your bag, and if they see a liquid container larger than 3.4 fl oz, they will confiscate it. Packing it correctly and removing the bag at security speeds up the process and prevents delays.

Liquids in checked baggage

Checked bags have no fluid ounce limit for most household liquids. You can pack full-size bottles of shampoo, lotion, perfume, and other toiletries without restriction. However, some items are classified as hazardous materials and have their own rules even in checked baggage.

Alcohol (wine, spirits, beer) is allowed in checked baggage but limited to 5 liters per passenger, and only one liter can be in a single container. Paint, paint thinner, and certain cleaning products are prohibited in both carry-on and checked baggage. Aerosol cans (hairspray, deodorant, sunscreen spray) are allowed in checked baggage in limited quantities — usually one container per passenger, and the airline must approve it.

If you are traveling with anything you think might be hazardous, check your airline's website before packing. Rules vary slightly between carriers, and some items require special handling or advance notice.

International flights and different country rules

The 3.4 fl oz rule applies to flights departing from the United States. If you are flying internationally, the rule still applies for your carry-on bag on the outbound flight. However, if you are connecting through another country or flying out of a foreign airport, that country's security rules may differ.

Many countries follow the same 3.4 fl oz (100 ml) standard because it aligns with international aviation security guidelines. However, some airports are stricter. If you are flying out of Canada, the UK, or the EU, the limit is the same. If you are unsure about a specific country, contact your airline or check the airport's website before you travel.

One important note: if you buy liquids in a duty-free shop after passing security, you can bring them on the plane in your carry-on, even if they exceed 3.4 fl oz. They must be in a sealed, tamper-evident bag provided by the shop. Do not open them before boarding.

What happens if you try to bring oversized containers

TSA agents screen carry-on bags with X-ray machines and physical inspection. If they find a liquid container larger than 3.4 fl oz, they will confiscate it. You do not get it back — it goes into a disposal bin. This happens at the checkpoint, so you lose the item and the money you spent on it.

There is no fine or penalty beyond losing the item itself. TSA does not issue citations for honest mistakes. However, if an agent suspects you deliberately tried to sneak a prohibited item through, they may call local police, though this is rare for liquid violations.

The best way to avoid this is to check container sizes before you pack. If you are unsure whether something counts as a liquid, pack it in checked baggage instead. Checked bags are screened too, but the rules are more lenient, and you will not lose the item at the checkpoint.

Travel-size alternatives and where to buy them

If you do not want to buy travel sizes before your trip, you can purchase them at most airports after you pass security. Duty-free shops, Hudson News, and other airport retailers sell small bottles of shampoo, lotion, sunscreen, and other toiletries. Prices are higher than retail stores, but the convenience is worth it if you forgot to pack travel sizes.

Before your trip, you can buy travel-size kits at drugstores like CVS and Walgreens, at big-box retailers like Target and Walmart, or online through Amazon. Many brands sell their own travel sets. This is usually cheaper than buying at the airport and gives you more time to organize your packing.

Another option is to use solid alternatives: solid shampoo bars, solid deodorant, solid perfume, and bar soap all avoid the liquid rule entirely and work well for travel. These often last longer than liquid versions and take up less space.

Frequently Asked Questions

Can I bring a full water bottle through security?

No. Water is a liquid and must follow the 3.4 fl oz rule. You cannot bring a full water bottle through TSA security. However, you can bring an empty reusable bottle and fill it at a water fountain or refill station after you pass security. Many airports have these stations near gates.

Does toothpaste count as a liquid?

Yes. Toothpaste is classified as a gel and must be 3.4 fl oz or smaller. A standard tube of toothpaste is usually 4.6 to 6 fl oz, so it exceeds the limit. Buy a travel-size tube (0.85 fl oz is common) or pack your regular tube in checked baggage.

What if my container says 100 ml but I am not sure how many fluid ounces that is?

100 milliliters equals 3.4 fluid ounces, so a 100 ml container is exactly at the limit and will pass through security. Anything labeled 100 ml or less is fine. If the label shows milliliters only, use this conversion: 100 ml = 3.4 fl oz, 50 ml = 1.7 fl oz.

Can I bring multiple 3.4 fl oz bottles if they fit in my quart-sized bag?

Yes. You can bring as many 3.4 fl oz containers as fit inside one clear quart-sized bag. There is no limit on the number of containers, only on the size of each one and the size of the bag they go in. Remove the bag at security and place it in the screening bin.

Are there any liquids that are exempt from the 3.4 fl oz rule in carry-on?

Yes. Medications in liquid form (like liquid insulin or cough syrup) are exempt if you declare them to TSA. Baby formula and breast milk are also exempt. Gel or liquid food items like peanut butter, honey, and yogurt are technically subject to the rule but are rarely confiscated if they are small. When in doubt, declare the item to the agent.