The TSA rules for carry-on bags are simpler than most people think

You can bring one carry-on bag and one personal item (like a purse or laptop bag) through security. The TSA does not set a strict size limit for carry-on bags — instead, your airline does. Most airlines allow bags up to 22 inches long, 14 inches wide, and 9 inches deep, but check your specific airline's website because some budget carriers have smaller limits. The real restrictions are not about size: they are about what you cannot bring at all, and what you can bring only in limited amounts.

The single biggest rule is the 3-1-1 liquid rule. You can bring liquids, gels, and aerosols through security only if each container holds 3.4 ounces (100 milliliters) or less, all containers fit inside one clear quart-sized plastic bag, and you have only one bag. This applies to toothpaste, shampoo, conditioner, lotion, sunscreen, deodorant, peanut butter, yogurt, jam, and anything else that is not solid at room temperature. Solid foods like bread, fruit, and cheese are fine. Once you pass security, you can buy larger bottles of liquids in the airport and bring them on the plane.

Key Takeaways

  • Liquids, gels, and aerosols must be 3.4 ounces or smaller per container, and all containers must fit in one clear quart-sized bag.
  • Solid foods, electronics, books, and clothing have no carry-on restrictions as long as they fit in your bag.
  • Weapons, sharp objects, and tools are banned from carry-on bags entirely — these must go in checked luggage or stay home.
  • Your airline, not the TSA, sets the size limit for your carry-on bag, so check your airline's website before packing.
  • Items you buy after passing security, including liquids and sharp objects, can go in your carry-on because they were screened at the point of sale.

Items that are completely banned from carry-on bags

Weapons cannot go in your carry-on under any circumstances. This includes guns, knives with blades longer than 2.36 inches, box cutters, razors, ice picks, and swords. Sporting equipment like baseball bats, hockey sticks, and ski poles are also banned from the cabin. If you need to travel with any of these, they must go in your checked bag, and some airlines require advance notice.

Flammable items are banned because they pose a fire risk in the pressurized cabin. This includes lighter fluid, paint thinner, gasoline, and most aerosol cans (though some personal-care aerosols like deodorant are allowed under the 3.4-ounce rule). Fireworks, flares, and ammunition are also prohibited. Explosives and materials that could be used to make explosives are federal crimes to bring on a plane, even in checked luggage.

Tools larger than 7 inches are banned from carry-on bags. This means no hammers, wrenches, saws, or drills. Hand tools under 7 inches — like a small screwdriver or multi-tool with a blade under 2.36 inches — are allowed. Power tools are banned entirely, even in checked bags on some airlines.

Electronics and batteries: what the rules actually are

Laptops, tablets, phones, cameras, and headphones are all fine in your carry-on. You will need to remove your laptop and place it in a bin at security, but the device itself is not restricted. Portable chargers and power banks are allowed, but lithium batteries have limits: you can bring two spare lithium batteries in your carry-on, and they must be in your personal item or carry-on bag, not checked luggage. This is because lithium batteries can overheat in the cargo hold.

E-cigarettes and vaping devices must stay in your carry-on bag, not checked luggage, because the battery poses a fire risk in the cargo hold. You cannot use them on the plane. Regular cigarettes are allowed in carry-on bags but cannot be smoked on the flight.

Medications, medical devices, and personal care items

Prescription and over-the-counter medications in pill, tablet, or capsule form have no carry-on restrictions — you can bring as much as you need. Liquid medications like insulin or cough syrup are allowed in reasonable quantities beyond the 3.4-ounce limit if you declare them at security. Tell the TSA officer you have liquid medication before you go through the scanner.

Medical devices like CPAP machines, nebulizers, and oxygen concentrators are allowed in carry-on bags. Syringes and needles are allowed if they are accompanied by medication or a medical device. Inhalers, EpiPens, and other emergency medications are not restricted.

Personal care items like deodorant, shampoo, and toothpaste follow the 3.4-ounce liquid rule. Solid deodorant is fine in any amount. Razors with disposable cartridges are allowed, but straight razors and safety razors are banned because the blade is exposed.

Food and drinks: what you can and cannot bring

Solid foods are allowed in carry-on bags with no restrictions. You can bring sandwiches, fruit, vegetables, cheese, crackers, cookies, and chocolate. Peanut butter, jam, honey, and other spreads are considered gels and must follow the 3.4-ounce rule. Soups, yogurt, and pudding are also gels and must be 3.4 ounces or smaller.

You cannot bring liquids through security, including water, juice, coffee, and milk. However, you can bring an empty water bottle through security and fill it at a water fountain or refill station after you pass the checkpoint. Many airports now have bottle-filling stations near the gates.

Items that depend on your airline's rules

Some items are allowed by the TSA but restricted by individual airlines. Sporting equipment like tennis rackets, golf clubs, and surfboards are allowed by the TSA but many airlines charge a fee or require them to be checked. Musical instruments are allowed in carry-on bags if they fit, but large instruments like cellos or double basses usually must be checked or require a seat purchase.

Lighters are a gray area: the TSA allows one disposable lighter in your carry-on bag (not in checked luggage), but some airlines ban them entirely. Check your airline's website before packing a lighter. Matches are allowed only in carry-on bags, not checked bags.

Dry ice is allowed in carry-on bags in limited quantities (2.2 pounds or less) if it is properly packaged and does not seal the container completely. It must be declared to the airline in advance. Gel ice packs are allowed as long as they are completely frozen solid when you go through security.

How to pack efficiently within the rules

Start by checking your airline's website for their specific carry-on size limits and any restrictions on items like sporting equipment or musical instruments. Pack your liquids in a separate clear quart-sized bag and place it where you can easily remove it at security. Put heavier items at the bottom of your bag and lighter items on top to distribute weight evenly.

If you are unsure whether an item is allowed, the TSA has a searchable database called "What Can I Bring?" on their website where you can type in any item and see the rules. You can also ask TSA officers at security if you have questions before you pack — they will give you a straight answer rather than guessing.

Frequently Asked Questions

Can I bring a full-size bottle of shampoo if I buy it after security?

Yes. Once you pass through security, you can purchase full-size bottles of shampoo, lotion, or any other liquid in the airport and bring them on the plane in your carry-on bag. The restriction only applies to items you bring through security.

Are scissors allowed in carry-on bags?

Scissors with blades shorter than 4 inches are allowed in carry-on bags. Scissors with longer blades must go in checked luggage. The rule is based on blade length, not total size.

Can I bring my laptop charger and power bank on the plane?

Yes. Laptop chargers and power banks are allowed in carry-on bags. If your power bank contains a lithium battery, you can bring up to two spare lithium batteries in your carry-on, but they must not be in checked luggage.

What happens if I accidentally pack a banned item in my carry-on?

TSA officers will find it during screening and confiscate it. You will not be fined or arrested for an honest mistake. If you realize you have a banned item before you reach security, you can go back and check it or leave it behind.

Can I bring a lighter or matches on the plane?

One disposable lighter is allowed in your carry-on bag only, not in checked luggage. Matches are allowed only in carry-on bags. Some airlines ban lighters entirely, so check your airline's policy before packing.