The 3-1-1 rule limits carry-on liquids to containers of 3.4 ounces (100 ml) or less, all fitting inside one quart-sized clear bag, with one bag per passenger. It applies to anything pourable, spreadable, sprayable, or squeezable. Medications, breast milk, and infant formula are exempt when declared at the checkpoint.
What each number in 3-1-1 means
A half-empty 8 oz bottle of shampoo is still refused, because officers judge the container, not the contents. Decant into travel bottles instead, or pack the full-size bottle in checked baggage.
3: each container may hold no more than 3.4 oz (100 ml). The printed container size is what counts, not how much is left inside.
1: everything must fit inside one clear, resealable quart-sized bag that closes without straining.
1: one bag per passenger. Each traveler in your party gets their own, including children.
What TSA counts as a liquid
The category is much broader than drinks. If you can pour it, spread it, spray it, pump it, or squeeze it, it falls under the rule — including gels, creams, pastes, aerosols, and many foods.
Several categories are exempt from both the 3.4 oz limit and the quart bag. They must be declared to an officer before screening and are inspected separately.
Prescription and over-the-counter medications, including liquids, gels, and creams, in reasonable quantities for your trip.
Breast milk, baby formula, and juice for an infant or toddler — the child does not have to be traveling with you.
Ice packs, gel packs, and freezer packs used to keep medication or milk cold.
Liquid nutrition, feeding supplies, and contact lens solution when medically necessary.
Duty-free liquids bought abroad and sealed in a tamper-evident bag with a same-day receipt.
Anything bought past the checkpoint — airside purchases have no size limit at all.
How liquids are screened, step by step
Keep the quart bag reachable — Store it in an outer pocket or at the top of your carry-on so you can lift it out without unpacking everything at the belt.
Put it in its own bin — In standard lanes the bag comes out and lies flat in a bin. TSA PreCheck lanes normally let liquids stay inside your bag.
Declare oversized liquids first — Say what you are carrying before your bag enters the X-ray. Medications, breast milk, and formula are screened separately.
Expect a secondary test — Officers may open a container, run a bottle scanner, or swab the outside. This is routine and does not mean the item is prohibited.
Refill after security — Fill an empty bottle at a fountain or bottle filler and buy any size of drink airside.
Where travelers get caught out
Assuming a partly used oversized bottle passes — the container size is what matters.
Forgetting food: hummus, yogurt, salsa, jam, and soup are liquids under the rule.
Overstuffing the quart bag so it will not close flat.
Leaving a full water bottle in a side pocket; empty it before the checkpoint.
Believing a gallon-sized bag is acceptable because the total volume is small.
Frequently Asked Questions
What is the TSA 3-1-1 rule?
It limits carry-on liquids to containers of 3.4 oz (100 ml) or less, all fitting in one quart-sized clear bag, with one bag per passenger. Liquids, gels, aerosols, creams, and pastes are all covered.
How many 3.4 oz bottles can you bring?
As many as genuinely fit in one quart bag that still closes — usually six to nine travel bottles depending on their shape. There is no separate count limit.
Does the 3-1-1 rule apply to checked bags?
No. Checked baggage has no 3.4 oz limit for ordinary toiletries. Aerosols and alcohol have their own volume limits, and flammable liquids are prohibited outright.
Do medications have to fit in the quart bag?
No. Prescription and over-the-counter medications, including liquids, are exempt in reasonable quantities. Declare them at the checkpoint for separate screening.
Can you bring liquids bought after security?
Yes. The rule only applies at the checkpoint, so any size of drink or liquid bought airside can be carried onto the plane.