Carry-On Liquid Limits

You can take containers of 3.4 ounces (100 milliliters) or less on a plane, and all of them must fit in one quart-size clear bag. That is the TSA's 3-1-1 rule, and it applies to every liquid, gel, aerosol, cream, and paste in your carry-on. Checked bags have no container size limit, and a short list of exemptions covers medications, infant formula, and duty-free purchases.

The 3-1-1 rule, precisely

The name is a memory aid for three numbers:

• 3: each container holds 3.4 ounces (100 ml) or less.
• 1: all containers fit in one quart-size, clear, resealable bag.
• 1: one bag per passenger.

All three conditions apply at once. A 3-ounce bottle that does not fit in the bag fails. A second quart bag fails. The bag must close, so a stuffed bag that will not seal can be rejected too. At the checkpoint, the liquids bag usually comes out of your carry-on and goes in a bin on its own, so pack it where you can reach it in one motion.

The rule exists for screening speed, not chemistry. Limiting every passenger to small containers in one transparent bag lets officers clear liquids at a glance instead of opening every case. Knowing that helps you predict edge cases: anything that slows the glance, like an opaque oversized container, gets pulled.

It is the container size, not the contents

This is the mistake that loses the most toiletries at checkpoints. The limit applies to the container's labeled capacity, not the amount inside. A 6-ounce bottle of shampoo with an inch left in the bottom is still a 6-ounce bottle, and it will be confiscated. Officers read the label; they do not estimate volume.

The fix is simple: decant. Buy a set of 3.4-ounce or smaller travel bottles, fill them from your full-size products, and the labeled capacity problem disappears. Travel-size versions of most products also exist, but refillable bottles are cheaper over more than a couple of trips.

What counts as a liquid

The TSA's working definition is broad: if you can spill it, spread it, spray it, pump it, or smear it, it is a liquid. That catches things travelers do not think of as liquids:

• Pastes: toothpaste, peanut butter, Nutella, hummus.
• Gels: hair gel, gel deodorant, jam and jelly.
• Aerosols: spray deodorant, dry shampoo, hairspray, shaving foam.
• Creams and lotions: moisturizer, sunscreen, foundation, mascara, lip gloss.
• Foods: yogurt, soup, salsa, maple syrup, canned goods with liquid.
• Oddballs: snow globes (the liquid inside counts), ice packs that have thawed, wet wipes are fine but the pouch of solution some come in may not be.

Solid items are exempt no matter the size: bar soap, solid stick deodorant, shampoo bars, solid perfume, powder makeup, and solid food. Large powders over 12 ounces may get extra screening on some routes but are not subject to 3-1-1.

The exemptions, and how to declare them

Three categories can exceed 3.4 ounces in a carry-on:

• Medications. Liquid prescription and over-the-counter medications are allowed in reasonable quantities, along with the ice packs or gel packs needed to keep them cold. They do not need to fit in the quart bag.
• Infant and child nourishment. Formula, breast milk, toddler drinks, and baby food are allowed in reasonable quantities, whether or not the child is traveling with you. Cooling accessories are allowed too.
• Duty-free liquids. Purchases made after security or on board can exceed the limit if they are sealed in a security tamper-evident bag (STEB) with the receipt visible inside. Do not open the bag before your final destination, especially if you connect through another airport and re-clear security.

Declaring is not paperwork. Before your items go on the belt, tell the officer you have liquid medication or formula over 3.4 ounces and take it out of your bag. It will be screened separately, sometimes with a quick vapor test, and you keep it. Travelers who bury an exempt item and hope it slides through cause their own delays; travelers who declare it up front usually add a minute or two.

TSA PreCheck does not change the liquid rules

PreCheck lets you leave the quart bag inside your carry-on instead of binning it separately, and that is the entire liquids benefit. The 3.4-ounce container limit, the one-bag limit, and the exemption rules are identical in the PreCheck lane. If your bottle is oversized, PreCheck will not save it.

Flying internationally

The 100 ml rule is close to a global standard. The EU, the UK, Canada, Australia, and most of Asia enforce the same container limit with the same one-bag structure. A few airports with new CT scanners have begun relaxing the limit, and some have then reinstated it when scanner rollouts stalled. The safe assumption is that every checkpoint on your itinerary enforces 100 ml, because the rule that matters is the one at the airport where you re-clear security, not the one where you started. Pack to the strictest rule on the route and you cannot be caught out.

Checked bags: no size limit, but pack smart

Liquids in checked luggage have no container size limit, with narrow exceptions for alcohol over 70 percent ABV (banned) and quantity caps on alcohol between 24 and 70 percent and on aerosols. Full-size shampoo, a bottle of wine, a jar of sauce: all fine to check.

Pressure and baggage handling are the real risks. Cabin holds are pressurized, but pressure still changes enough to force liquid past a loose cap. Tape or plastic-wrap the caps, bag each bottle, and pad them in the middle of the case away from the shell. A hard-shell case protects bottles from crushing better than a soft bag, but nothing protects your clothes from a cap that was not sealed.

Quick reference

Item	Carry-on	Checked
Toiletries (shampoo, lotion, toothpaste)	3.4 oz max per container, in quart bag	Any size
Aerosols (deodorant, hairspray)	3.4 oz max, in quart bag	Allowed, quantity capped
Liquid medication	Any reasonable amount, declare it	Any amount
Formula and breast milk	Any reasonable amount, declare it	Any amount
Water and drinks	3.4 oz max through the checkpoint	Allowed, seal well
Duty-free alcohol	Allowed in sealed STEB bag	Allowed, ABV rules apply
Solid toiletries (bars, sticks)	No limit	No limit

Packing toiletries around the rule

The quart bag is small, so treat it as a constraint to design around rather than fight:

1. Go solid where you can. Shampoo bars, bar soap, stick deodorant, and powder makeup never touch the quart bag. Every solid swap frees a slot.
2. Decant everything else. A week of most products fits in a 2-ounce bottle. Matching flat bottles pack tighter than a mix of shapes.
3. One bag, packed once. Keep a permanently packed liquids bag that lives with your suitcase. Refill it after each trip instead of rebuilding it before the next one.
4. Buy the big stuff there. Sunscreen for a beach week does not fit the rule. Buy it at the destination and abandon it.

Where the bag rides matters too: top layer or an outer pocket, never under the packing cubes. The full system, including where liquids sit relative to electronics at the checkpoint, is in our guide on how to pack a carry-on. And remember that liquids are only one gate; the bag itself has to pass the sizer, covered in the carry-on size guide.

Common questions

Is deodorant a liquid?

Depends on the form. Solid stick deodorant is not a liquid and has no size limit. Spray, gel, roll-on, and cream deodorants all count as liquids and must be 3.4 ounces or less in a carry-on. If the label says gel or the product smears, put it in the quart bag.

Can I bring a water bottle?

An empty bottle, yes, any size, any material. A filled one will not make it through the checkpoint unless it is under 3.4 ounces. The standard move is to carry an empty bottle through security and fill it at a fountain on the other side. Frozen liquids are technically allowed if completely solid at screening, but a partially melted bottle gets confiscated, so it is a gamble.

What are the rules for makeup?

Powder, pressed, and solid makeup is unlimited: eyeshadow, blush, powder foundation, lipstick, solid balms. Liquid and cream products follow 3-1-1: liquid foundation, mascara, liquid liner, concealer, nail polish, and cream blush all go in the quart bag. A typical makeup kit splits roughly in half, so pull the liquids out rather than binning the whole kit.

How strict is TSA about 3-1-1?

Strict on container size, mildly flexible on everything else. An oversized bottle is confiscated when spotted, and scanners flag liquids well. Officers rarely measure whether your bag is exactly a quart or count containers, but they have full discretion, and the busier the checkpoint, the less discussion you get. The only reliable strategy is to be clearly inside the rule.

Rules change, and individual officers make the final call at the checkpoint. When something matters, check TSA.gov before you fly; for other countries, check the airport security authority on your route.

A case built around the checkpoint

Liquid rules reward a carry-on that opens flat and gives the quart bag an obvious home. The TALO Cabin is a ribbed aluminum case with TSA-approved frame latches instead of zippers, so it opens cleanly at security and closes with the same even pressure every time, sized to standard cabin limits for the major US airlines. If you are still deciding what qualifies as a cabin bag in the first place, start with what counts as a carry-on.