The Basic Rule: Size, Weight, and What Airlines Actually Check

What you can bring on the plane depends on three things: your airline's size and weight limits, TSA rules about liquids and sharp objects, and what the specific airport screeners decide that day. Most airlines allow one carry-on bag (22 by 14 by 9 inches is the standard) plus one personal item like a purse or laptop bag. Weight limits are usually 25 pounds, though some budget airlines charge extra if you go over.

TSA screens for safety hazards, not comfort or convenience. They care most about liquids over 3.4 ounces, anything that could be a weapon, and items that could damage the plane. The rules are the same at every US airport, but individual screeners sometimes interpret them differently—so an item that passed in Denver might get flagged in Atlanta. If you are unsure about something specific, call the airport's TSA line before you go, or text a photo to the TSA's Ask TSA account on social media.

Pack heavier items in your carry-on and lighter things in checked luggage. Carry-on bags sit in the overhead bin, which has weight limits, and screeners notice if your bag looks suspiciously heavy. If your bag is overweight, the gate agent can make you check it at the last minute, which means you lose the ability to keep it with you.

Key Takeaways

  • Liquids, gels, and pastes must be 3.4 ounces or smaller and fit in a single quart-sized clear plastic bag; this includes shampoo, toothpaste, peanut butter, and yogurt.
  • Sharp objects like knives, box cutters, and scissors are prohibited in carry-on bags but allowed in checked luggage if they are wrapped so the blade cannot cut a screener.
  • Electronics larger than a laptop (like a full-sized printer or power drill) are usually prohibited, but phones, tablets, cameras, and headphones are always allowed.
  • Medications in their original labeled containers are allowed in any quantity, and you can bring a reasonable amount of food as long as it is solid—not liquid or gel.
  • Check your specific airline's website for their size and weight limits, because some budget carriers have stricter rules than the TSA standard.

Liquids, Gels, and Pastes: The 3.4-Ounce Rule

The TSA's liquid rule is the most confusing part of packing, because "liquid" includes things that do not look wet. A 3.4-ounce limit applies to shampoo, conditioner, lotion, toothpaste, deodorant, peanut butter, honey, jam, yogurt, mascara, eyeliner, foundation, sunscreen, and anything else that flows or spreads. If you are not sure whether something counts, assume it does.

All liquids must fit into a single quart-sized clear plastic bag—the kind that is roughly 7 by 8 inches. You get one bag per person. Each individual container must be 3.4 ounces or smaller; you cannot bring five 2-ounce bottles of shampoo because they would not all fit in the bag. Solid deodorant is allowed in unlimited quantities because it is not a gel. Solid food is allowed in unlimited quantities. Medications and baby formula are exempt from the liquid rule if they are medically necessary.

Pack your liquids bag where you can reach it easily, because screeners will ask you to remove it before you go through the scanner. If you forget and it is still in your bag, the screener will find it, and you will have to throw it away or step out of line to repack.

Sharp Objects and Tools You Cannot Bring

Anything with a blade or point longer than 7 inches is prohibited in carry-on luggage. This includes kitchen knives, box cutters, razors, scissors, and ice picks. Pocket knives and multi-tools with blades are also prohibited, even if the blade is small. Corkscrews with a blade are prohibited; a corkscrew without a blade is allowed.

All of these items are allowed in checked luggage if they are wrapped so the blade cannot cut a screener's hand. Wrap the blade in cloth or cardboard, tape it closed, and pack it in the middle of your suitcase, not on top. Do not tell the screener it is there unless the airline's website says you must declare it—most do not require a declaration, but a few do.

Tools like hammers, wrenches, screwdrivers, and saws are prohibited in carry-on but allowed in checked luggage. Drills and power tools are prohibited in both carry-on and checked luggage on passenger planes. If you need tools at your destination, rent them there or ship them ahead.

Electronics: What Stays in Your Bag and What Gets Screened

Phones, tablets, laptops, cameras, headphones, and portable chargers are always allowed in carry-on luggage. You will have to remove your laptop and large electronics from your bag at security, but you can put them back in once you are through the scanner. Tablets smaller than a standard notebook can sometimes stay in your bag during screening, but it depends on the screener and the scanner type—remove it to be safe.

Larger electronics like full-sized printers, desktop monitors, and power tools are prohibited in carry-on luggage because they do not fit in the overhead bin and they are too heavy. Some airlines allow them in checked luggage; others do not. Check your airline's website before you pack.

Lithium batteries are restricted. You can bring two spare lithium batteries in carry-on luggage if they are under 100 watt-hours each (most phone and camera batteries are). Larger batteries, like those for power tools or electric bikes, are prohibited in both carry-on and checked luggage. Vaping devices with lithium batteries are allowed in carry-on only, not checked luggage.

Food, Medications, and Baby Items

Solid food is allowed in unlimited quantities in carry-on luggage. Bring sandwiches, fruit, nuts, granola bars, cheese, and crackers without worry. Liquid or gel food—like peanut butter, yogurt, honey, jam, or hummus—must follow the 3.4-ounce liquid rule and fit in your quart-sized bag.

Medications in their original labeled containers are allowed in any quantity, even if they exceed the liquid limit. Bring your prescription bottles with your name on them. Over-the-counter medications like ibuprofen and cold medicine are allowed. Inhalers and EpiPens are allowed. If a medication is a liquid or gel, you do not need to put it in your liquids bag—just pack it separately and tell the screener if they ask.

Baby formula, breast milk, and baby food are exempt from the liquid rule in any quantity. You do not need to put them in a bag. Ice packs and frozen gel packs are allowed if they are completely frozen solid when you go through security; if they have any liquid on them, they count as liquids and must fit in your bag.

Items That Are Prohibited or Restricted

Firearms, ammunition, and realistic replica guns are prohibited in carry-on luggage. Real firearms are allowed in checked luggage only if they are unloaded, in a locked hard-sided container, and declared to the airline at check-in. Ammunition is allowed in checked luggage only in a manufacturer's container or a find ammunition box.

Lighters and matches are prohibited in carry-on luggage. You can bring one lighter in checked luggage if it has a safety mechanism, but matches are prohibited in both carry-on and checked luggage. Flammable liquids like paint thinner and lighter fluid are prohibited in both.

Sporting equipment like baseball bats, golf clubs, and ski poles are prohibited in carry-on but allowed in checked luggage. Some airlines charge an extra fee for sports equipment. Martial arts weapons like nunchucks and throwing stars are prohibited in both carry-on and checked luggage.

How to Pack Smart and Avoid Delays at Security

Organize your bag so screeners can see what is inside without unpacking everything. Put your liquids bag on top. Remove your laptop and large electronics before you reach the scanner. Wear shoes and a belt that are straightforward to remove. Empty your pockets completely—screeners will stop the line if they see anything in your pockets on the scanner.

If you are traveling with items you are unsure about, pack them in checked luggage instead of carry-on. It is better to lose checked luggage to a delay than to have a screener confiscate something at the gate. If a screener tells you something is prohibited, do not argue—they have the final say. You can ask to speak to a supervisor if you believe they are wrong, but this will delay your flight.

Arrive at security at least two hours before a domestic flight and three hours before an international flight. This gives you time to repack if something gets flagged. If you are traveling with a child, bring a change of clothes in your carry-on in case checked luggage is delayed.

Frequently Asked Questions

Can I bring a full-sized bottle of shampoo if I check my luggage?

Yes. The 3.4-ounce liquid rule applies only to carry-on luggage. You can pack full-sized bottles of shampoo, lotion, perfume, and other liquids in your checked bag without any limit. Make sure the bottles are sealed and pack them in a plastic bag in case they leak during the flight.

Are scissors allowed in carry-on luggage?

No. Scissors with blades longer than 7 inches are prohibited in carry-on luggage. Scissors with blades shorter than 7 inches are allowed only if the blades are rounded. Most regular household scissors are prohibited. Pack them in checked luggage instead.

Can I bring my laptop through security without removing it?

It depends on the airport and the type of security scanner. Most airports require you to remove laptops and place them in a bin. Some newer airports with advanced scanners allow laptops to stay in your bag. Remove your laptop to be safe—it takes five seconds and avoids a delay.

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

A screener will find it at the security checkpoint. You will have to throw it away, leave it with a friend, or go back to check it in your luggage if you have time. You will not be arrested or fined for an honest mistake. If you realize you packed something before you reach security, go back to your car or a trash can and dispose of it.

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

Yes. Phone chargers and portable power banks are allowed in carry-on luggage. Power banks with lithium batteries under 100 watt-hours are allowed; larger ones are prohibited. Check your power bank's label to see the watt-hour rating. Most standard phone chargers and power banks are well under this limit.