TSA 3-1-1 Liquids Rule Explained: Complete 2026 Guide

What Does the 3 Mean in TSA 3-1-1?

The 3 is the container limit: 3.4 fluid ounces. That odd number exists because the international standard is a round 100 millilitres, and 100 ml converts to roughly 3.4 fl oz. Travel-size products sold worldwide are built to that number, which is why a bottle labeled 100 ml and one labeled 3.4 oz are the same allowance.

Two things the 3 is not: it is not a total volume allowance across your bag, and it is not measured by how much product remains. It's a per-container capacity limit, applied to every qualifying container you carry.

What Does the First 1 Mean?

The first 1 is the bag: a single quart-sized (approximately one litre) clear, resealable plastic bag that holds all of your qualifying containers. Clear so officers can see the contents without opening it; resealable so it closes fully.

• Every qualifying container must actually fit inside — the bag has to close.
• An overstuffed or bulging bag can be rejected even if each container is compliant.
• A standard quart zip-top food bag or a purpose-made clear toiletry pouch of the same capacity both work.

Depending on the equipment in your lane, you may be asked to place the bag in a bin separately, or told to leave it in your carry-on. Follow the posted signage and the officer's instruction at that checkpoint.

What Does the Second 1 Mean?

The second 1 is the passenger allowance: one liquids bag per traveler. You cannot bring two quart bags for yourself. Each person in your party — including children — has their own allowance, so a family of four can carry four bags in total, and an adult may carry a child's bag for them.

Why Container Size Matters

The reason is practical: an officer at the belt can't verify how much liquid is in an opaque bottle, and the marked size is the only objective measure available in seconds. The same logic explains why a partially used 100 ml bottle is fine — its capacity never changes.

What Counts as a Liquid Under the 3-1-1 Rule?

The rule covers five categories, all screened the same way:

• Liquids — anything pourable, such as drinks, shampoo or contact lens solution.
• Gels — hair gel, gel deodorant, hand sanitizer.
• Creams — lotion, sunscreen, shaving cream.
• Pastes — toothpaste, peanut butter, thick spreads.
• Aerosols — hairspray, dry shampoo, spray sunscreen.

For an item-by-item breakdown of specific toiletries, drinks and foods, see the carry-on liquid packing guide.

What About Solid Items?

Products that are genuinely solid fall outside the liquids rule entirely: they have no container-size limit and don't belong in the quart bag. Common examples are bar soap, solid stick deodorant, shampoo bars, toothpaste tablets, powders and pressed cosmetics.

Form, not brand or purpose, decides the treatment — which is why stick and gel deodorant are handled differently, and why powder makeup escapes a limit that liquid foundation does not. Officers may still inspect or test any item.

Exceptions to the TSA 3-1-1 Rule

A small set of categories is handled outside the standard allowance. "Exception" does not mean unrestricted: these items are permitted in reasonable quantities for the trip, must be declared, and are screened separately — often by opening, testing or imaging the container.

• Medically necessary liquids, including liquid medication
• Breast milk, formula, toddler drinks and baby food
• Ice packs, gel packs and cooling accessories needed for the items above
• Qualifying duty-free liquids in a sealed, tamper-evident bag

Medication and Medically Necessary Liquids

At the rule level: liquid medication is exempt from both the 3.4 oz container limit and the quart-bag requirement, in reasonable quantities for your itinerary. You must remove it from your bag and tell the officer before screening begins, and the container may be tested. Labeling isn't federally required, though original packaging speeds things up.

Traveler guide: bringing medication on a plane →

Breast Milk, Formula & Child-Related Liquids

TSA treats breast milk, formula, toddler drinks and baby or toddler food as medically necessary liquids. They are permitted in reasonable quantities above 3.4 oz, do not need to fit in the quart bag, and are screened separately. Breast milk is allowed whether or not the child is travelling with you, and the related ice packs or freezer packs are allowed even if partially melted.

Remove these items and declare them at the start of screening. You can ask about alternative screening if you'd rather the container not be opened. This exception is specific to those categories — it doesn't extend to ordinary toiletries carried for a child.

Duty-Free Liquids and International Connections

Duty-free liquids over 3.4 oz are not automatically exempt. They can generally continue through a U.S. connection only when they remain sealed in a secure, tamper-evident bag with the receipt visible inside and dated within the previous 48 hours. If the bag shows signs of tampering — or you open it before your final destination — the standard limit applies again and the liquid may be surrendered.

Frozen Liquids and Ice

Physical state at the moment of screening is what matters. Items frozen solid may be screened as solids; once they're slushy, partially melted, or there's liquid pooling in the container, the 3-1-1 limit applies again. Ice and gel packs supporting medically necessary liquids or child-related liquids are allowed even when partially melted, provided you declare them.

Does the TSA 3-1-1 Rule Apply to Checked Baggage?

No. 3-1-1 is a carry-on screening rule; there is no 3.4 oz container limit in checked bags. That is not the same as "anything goes" — several other regimes apply:

• Aerosols: FAA limits toiletry aerosols to containers of 18 oz (500 ml) or less, about 70 oz total per passenger, with caps protected.
• Alcohol: above 24% and up to 70% ABV is capped at 5 litres per passenger in retail packaging; above 70% ABV is prohibited.
• Flammable and hazardous liquids: fuels, solvents, spray paint and bleach are forbidden in both bags.
• Airline policy: carriers can be stricter than the federal minimum.

Is the TSA 3-1-1 Rule Used Worldwide?

"3-1-1" is TSA's branding for a U.S. requirement. TSA is a U.S. federal agency with no authority over screening in other countries. Many aviation authorities apply a comparable 100 ml container standard with a one-litre transparent bag, but the details — bag dimensions, exception handling, and whether newer imaging equipment relaxes the limit — vary by country and even by airport. Check the rules published by the security authority for each airport where you will be screened.

What If You're Connecting Through a U.S. Airport?

If your itinerary routes you back through a TSA checkpoint — which is common for international arrivals who collect and re-check baggage before an onward domestic flight — the U.S. rule applies again at that point, regardless of what was permitted at your origin airport. Liquids bought after your first screening, including duty-free, may have to satisfy the conditions above to continue. Procedures differ by airport and itinerary, so confirm with your airline when planning a tight connection.

3-1-1 Rule Examples

Does the TSA 3-1-1 Rule Apply to My Item?

Answer two or three questions to see whether the standard rule governs your item, or whether an exception or a different set of restrictions takes over.

Common TSA 3-1-1 Rule Mistakes

• Reading 3.4 oz as a total liquid allowance rather than a per-container limit.
• Ignoring the capacity printed on the container.
• Assuming an oversized bottle qualifies because it's almost empty.
• Forgetting that gels, creams, pastes and aerosols are covered too.
• Assuming all medication follows the ordinary rule instead of the exception.
• Expecting checked baggage to follow the identical 3-1-1 system.
• Treating TSA's rule as worldwide law at every airport on the trip.
• Putting solid toiletries in the quart bag and crowding out items that actually need to be there.

Frequently Asked Questions