The TSA's Basic Rule: Liquids, Gels, and Aerosols

The 3-1-1 rule is the core limit for carry-on bags: you can bring liquids, gels, and aerosols only if each container holds 3.4 ounces (100 milliliters) or less, all containers fit into one quart-sized clear plastic bag, and you pack only one bag per person. This rule applies at U.S. airports and covers items like shampoo, toothpaste, lotion, sunscreen, peanut butter, yogurt, and jam. Solid items—like a bar of soap or a stick of deodorant—are not limited by the 3-1-1 rule and can be any size.

The TSA (Transportation Security Administration) enforces this rule because liquids and gels can be harder to screen for threats. If your container is larger than 3.4 ounces, even if it is half full, you cannot bring it in your carry-on. You must pack it in checked luggage instead. The quart-sized bag itself is not provided by the airport; you bring your own or pick one up at a travel store.

Key Takeaways

  • Liquids, gels, and aerosols must be 3.4 ounces or smaller per container and fit in one quart-sized clear plastic bag.
  • Solid items like bars of soap, deodorant sticks, and peanut butter are not subject to the 3-1-1 rule and can be any size.
  • Common carry-on items include books, electronics, clothing, shoes, and personal documents—pack these freely.
  • Weapons, sharp objects, tools, and certain sporting equipment are banned from carry-on bags and must go in checked luggage or stay home.
  • Medications in pill or tablet form are allowed in carry-on bags without size limits, but liquids and gels must follow the 3-1-1 rule.

Electronics and Chargers You Can Bring

Laptops, tablets, phones, cameras, and e-readers are all allowed in carry-on bags. You will need to remove your laptop and large electronics from your bag at security screening so they can be X-rayed separately. Chargers, cables, and power banks are permitted, though power banks with more than 100 watt-hours may be restricted—check your specific model's watt-hour rating before you travel.

Headphones, smartwatches, portable speakers, and gaming devices are fine to pack. If you are traveling with expensive electronics, keeping them in your carry-on rather than checked luggage protects them from damage and theft.

Clothing, Shoes, and Personal Items

Everyday clothing, shoes, belts, hats, and accessories have no restrictions in carry-on bags. You can pack as many clothes as your bag will hold. Underwear, socks, pajamas, jackets, and swimwear are all allowed. Shoes do not need to be removed at security unless they have metal components that trigger the detector.

Personal care items that are solids or solid-form products—like a toothbrush, hairbrush, razor (with blade), nail clippers, and tweezers—are allowed. Liquid or gel versions of these items (liquid soap, shampoo, toothpaste) must follow the 3-1-1 rule.

What Is Banned from Carry-On Bags

Weapons of any kind are prohibited in carry-on bags. This includes guns, knives (even small pocket knives), box cutters, ice picks, and martial arts weapons. Tools like hammers, screwdrivers, wrenches, and saws are also banned from carry-on. If you need to travel with tools or weapons, they must go in checked luggage, and some items may be banned from checked bags as well—check with your airline before packing.

Sporting equipment with sharp or heavy components has mixed rules. Baseball bats, cricket bats, and golf clubs are banned from carry-on but may be allowed in checked bags. Skis, snowboards, and fishing rods are typically allowed in checked luggage. Lighters and lighter fluid are banned entirely from both carry-on and checked bags. Flammable items like paint, gasoline, and fireworks cannot travel on planes at all.

Certain self-defense items are restricted. Pepper spray and mace are banned from carry-on bags, though one 2% by mass tear gas self-defense spray is allowed in checked luggage only if it is equipped with a safety mechanism. Brass knuckles and similar items are prohibited.

Medications and Medical Devices

Prescription and over-the-counter medications in pill, tablet, or capsule form have no size or quantity limits in carry-on bags. You do not need to declare them, but it is wise to keep them in their original labeled containers so security can identify them if asked. If your medication is a liquid or gel—like insulin, cough syrup, or a topical cream—it is exempt from the 3-1-1 rule and can exceed 3.4 ounces, but you must declare it to security at the checkpoint.

Medical devices like inhalers, EpiPens, and glucose meters are allowed. If you use a CPAP machine or other medical equipment, you can bring it in your carry-on. Syringes are permitted if they are accompanied by medication or medical documentation. Liquid medical supplies like saline solution or breast milk are also exempt from the 3-1-1 limit.

Food, Drinks, and Perishables

Solid foods are allowed in carry-on bags with no restrictions. You can pack sandwiches, fruit, vegetables, cheese, crackers, cookies, chocolate, and nuts. Peanut butter, jam, honey, and other spreads are considered gels and must follow the 3-1-1 rule—a container larger than 3.4 ounces cannot go in your carry-on.

Empty water bottles are allowed through security, and you can fill them at a water fountain or bottle-filling station after you pass the checkpoint. Beverages, yogurt, soup, and other liquids cannot pass through security in your carry-on, but you can purchase them after screening. Frozen items like ice packs are allowed if they are completely frozen solid at the checkpoint; partially thawed items may be confiscated.

Documents, Money, and Valuables

Passports, driver's licenses, boarding passes, and travel documents have no restrictions. Cash, credit cards, and jewelry can be packed freely in your carry-on. Valuable items like cameras, laptops, and watches are actually safer in your carry-on than in checked luggage, where they are more likely to be damaged or lost.

If you are traveling internationally, check whether your destination has restrictions on items you plan to bring—some countries limit the amount of cash you can enter with or prohibit certain electronics or medications. Your airline's website lists country-specific rules.

Frequently Asked Questions

Can I bring a lighter in my carry-on bag?

No. Lighters are banned from both carry-on and checked bags on all flights. This includes disposable lighters, refillable lighters, and lighter fluid. If you smoke, you will need to wait until you land.

Is a pocket knife allowed in carry-on luggage?

No. Any knife, including pocket knives and multi-tools with blades, is prohibited in carry-on bags. These items must stay home or be packed in checked luggage, though some airlines restrict knives from checked bags as well.

Can I bring my own food through security?

Yes, solid foods like sandwiches, fruit, and snacks are allowed through security. Liquids and gels like peanut butter, yogurt, and honey must follow the 3-1-1 rule. You can also purchase food after you pass the checkpoint.

Do I need to remove my shoes at security?

Not always. You only need to remove shoes if they have metal components that trigger the metal detector. Most standard shoes can stay on. Follow the TSA officer's instructions at your specific checkpoint.

Can I bring my medication in a carry-on bag?

Yes. Medications in pill or tablet form have no limits. Liquid or gel medications like insulin or cough syrup are exempt from the 3-1-1 rule but must be declared to security. Keep medications in labeled containers.