8.1 The 3-1-1 Liquids Rule

8.1 The 3-1-1 Liquids Rule

Quick answer: You may bring a quart-sized bag of liquids, aerosols, gels, creams and pastes in a carry-on and through the checkpoint. Containers must be travel-sized: 3.4 ounces (100 milliliters) or less per item. One quart-size clear plastic zip-top bag. One bag per passenger. Place the items in that small bag and separate them from the carry-on to facilitate screening. Pack containers larger than 3.4 ounces or 100 milliliters in checked baggage. Any liquid, aerosol, gel, cream, or paste that alarms requires additional screening. Computed tomography (CT) has not abolished 3-1-1.

This section trains published 3-1-1 logic for the TSO Assessment Battery (TAB) and for the live checkpoint. It does not teach Sensitive Security Information (SSI) resolution trees. You are learning the public carry-on versus checked map for liquids, aerosols, gels, creams, and pastes, and the visual discipline image-interpretation aptitude requires: a travel-size bottle in a clear bag is not the same problem as a full-size toiletry buried in clothing, and an alarm is not a free pass because the label says 3.4 ounces.

The 3-1-1 mnemonic

TSA's Liquids, Aerosols, and Gels Rule and the Travel Checklist use the same three numbers. Memorize them as a packing instruction, not as a slogan.

Read the table left to right the way a traveler packs. The container is 3.4 ounces or 100 milliliters or less. Those containers go in one quart-size clear plastic zip-top bag. That bag is one per passenger. TSA's checklist states the same three bullets: 3.4 ounces or less per container; 1 quart size, clear, plastic, zip top bag (all liquids must fit in bag); 1 bag per passenger.

Do not invent a fourth number. There is no published "if it is half empty, the bottle may be 8 ounces" exception. The public rule is about travel-sized containers of 3.4 ounces (100 milliliters) or less per item. A 12-ounce shampoo bottle with two ounces left is still a container larger than 3.4 ounces. Pack it in checked baggage.

What counts as a 3-1-1 item

The live rule covers liquids, aerosols, gels, creams and pastes. That family is broader than drinking water. Common checkpoint items in this family include toothpaste, shampoo, conditioner, mouthwash, and lotion. Those five are not a closed list. They are the everyday toiletries that show up in a quart bag every morning at a U.S. checkpoint. If the substance pours, sprays, spreads, or squeezes, treat it as a LAG unless a published exemption applies (Section 8.2).

Aerosol toiletries are still 3-1-1 when they travel in carry-on: the can must be 3.4 ounces (100 milliliters) or less and it must fit in the one quart bag. Gels and pastes are not a loophole. Toothpaste is a paste. Hair gel is a gel. They belong in the bag.

Separate the bag; pack the rest

TSA's liquids page is operational, not decorative: placing these items in the small bag and separating them from your carry-on baggage facilitates the screening process. The Travel Checklist tells travelers to put the 3-1-1 bag in the front pocket of the carry-on for accessibility, and, in a standard screening lane, to remove the 3-1-1 liquids bag and place it in the bin.

That is the public belt picture you should be able to describe without unpublished SOP:

• Start packing from an empty bag so leftover full-size toiletries are not still in a pocket.
• Keep the quart bag accessible, not buried under shoes and cables.
• In a standard lane, the 3-1-1 bag comes out and goes in a bin.
• Pack items in containers larger than 3.4 ounces or 100 milliliters in checked baggage.

The checklist also reminds travelers that how you pack affects screening. Security Screening says officers may instruct travelers to separate foods, powders, and other materials that clutter bags and obstruct a clear X-ray image. A jam-packed toiletry pouch next to a laptop and a sweater is a clutter problem even when every bottle is travel-sized.

Alarms are not a size waiver

TSA states the alarm rule in one sentence: any liquid, aerosol, gel, cream or paste that alarms during screening will require additional screening. Travel-size does not cancel an alarm. A labeled 3.4-ounce bottle that alarms is still an unresolved LAG. Additional screening is the published next step, not "it is 3-1-1, so it clears." If the alarm cannot be resolved under the procedures in use at that lane, the item does not get a special public exception just because it fit in the quart bag.

The same sentence is the image-interpretation reminder. A bottle-shaped organic-density mass can be shampoo. It can also be a threat liquid. You do not invent a color code that TSA.gov does not publish. You do recognize a container of liquid, you do notice overlap with electronics or clothing, and you do treat an alarm as a reason for additional screening.

Standard lanes, TSA PreCheck, and CT — 3-1-1 is not abolished

Standard screening requires travelers to remove items and place them on the X-ray belt. The checklist is specific: remove the 3-1-1 bag; empty pockets; remove personal electronic devices larger than a cell phone and place them in a bin with nothing on or under them.

TSA PreCheck screening is different in the typical case: travelers do not need to remove shoes, laptops, liquids, belts, and light jackets. That is the public benefit language. It is not a guarantee. TSA's screening page states that TSA uses unpredictable security measures throughout the airport and that no individual is guaranteed expedited screening. A PreCheck traveler can still be directed to remove the quart bag, to use a standard lane, or to undergo additional screening. Do not write "PreCheck never takes liquids out" on an assessment item.

Computed tomography at the checkpoint is the newest carry-on X-ray. TSA's CT page says the machines create a 3-D image that can be rotated 360 degrees and that computers can automatically detect explosives, including liquids. Under current screening procedures for this technology, laptops are allowed to remain inside the bag. In the future, the goal is to keep laptops and 3-1-1 liquids inside of the bag during checkpoint screening.

Read that last sentence twice. The future goal is 3-1-1-in-bag. The current CT procedure called out on that page is laptops in the bag. That is not a public statement that 3-1-1 has been abolished. Do not tell a traveler, and do not mark on a practice item, that CT means full-size liquids may now ride in carry-on. Until TSA publishes a change to the liquids rule itself, the 3-1-1 limits still describe what may be in the cabin bag.

Image discipline for LAGs

Image-interpretation aptitude still has to separate a travel-size bottle in a clear bag from a full-size bottle in a cluttered pouch. Clues that stay inside public training language:

• Container geometry: a small bottle, tube, or aerosol can versus a large toiletry bottle that will not fit the quart-bag story.
• Fill and overlap: liquid occupying a bottle, stacked with other bottles, or hidden under clothing and cables.
• Bag presentation: a clear zip-top bag laid out is what the liquids page asks for; a toiletry kit zipped inside the carry-on is what officers often have to unpack.
• Alarm logic: any LAG that alarms needs additional screening, including the travel-sized ones.

Clothing overlap does not rewrite 3-1-1. A 16-ounce lotion wrapped in a sweater is still a container larger than 3.4 ounces.

Realistic scenario

A traveler in a standard lane keeps a 3.4-ounce toothpaste, a 3.4-ounce shampoo, a 3.4-ounce conditioner, a 3.4-ounce mouthwash, and a 3.4-ounce lotion in a quart-size clear zip-top bag, plus a 12-ounce hotel shampoo in the same carry-on. The five travel-size items match 3-1-1: they are 3.4 ounces or less, they fit in one clear quart bag, and that bag is the one bag for that passenger. The officer's public instruction is to remove the 3-1-1 bag and place it in the bin. The 12-ounce hotel shampoo does not become legal because the other bottles are travel-size. It belongs in checked baggage. If the travel-size mouthwash alarms, it still needs additional screening. If the same traveler is in a PreCheck lane, liquids typically stay in the bag — and if the lane or the officer directs otherwise, that is still lawful, because no individual is guaranteed expedited screening. If the bag is running a checkpoint CT unit, the laptop may stay in the bag under current published CT procedure; 3-1-1-in-bag remains a future goal. The final decision rests with the TSA officer on whether an item is allowed through the checkpoint.