The TSA 3-1-1 liquids rule, item by item

At US airport checkpoints, TSA lets each passenger carry one quart-size bag of liquids, aerosols, gels, creams and pastes, and every container in it must be 3.4 ounces (100 milliliters) or less. Bigger containers go in a checked bag, unless they fall under an exemption TSA names, such as medicine, formula or breast milk.

Our take: pack the bag at home, go by the size printed on each container rather than how full it is, and switch to solid versions where you can. If you carry medicine or baby liquids over 3.4 ounces, tell the officer before screening starts. [S1] [S2] [S5]

3-1-1 at a glance

Original schematic, not TSA artwork. The limits and the exemption come from TSA’s liquids rule page, its FAQ and its medical screening page. [S1] [S2] [S5]

3.4 ounces per container, one quart bag each

TSA’s rule covers liquids, aerosols, gels, creams and pastes in your carry-on. Each one has to be in a travel-size container of 3.4 ounces (100 milliliters) or less, and they all go in one quart-size bag per passenger. TSA says putting them in that bag and taking it out of your carry-on makes screening easier. [S1] [S2]

The limit applies to the container. TSA says to pack items in containers larger than 3.4 ounces or 100 milliliters in checked baggage, so a big bottle that’s half empty still counts as big. [S1]

Bringing liquids over the limit means a bag check and a slower line, TSA’s Fairbanks office said in July 2026. Anything that alarms during screening gets extra screening. [S1] [S3]

Size printed on the container

Enter the size on the label to check it against 3.4 ounces (100 mL).

Where TSA pages differ

The rule page says to take the liquids bag out of your carry-on. TSA’s medical screening page says you don’t need to remove 3-1-1 liquids in TSA PreCheck lanes. Its CT scanner page says the goal is to someday leave 3-1-1 liquids in the bag, while current procedures for those scanners only let laptops stay in. None of these pages says the 3.4-ounce limit changes. We’d pack to the limit for every lane and follow what the officer at your lane says about the bag. [S1] [S5] [S10]

What counts as a liquid

TSA describes liquids as anything that can be spread, spilled, pumped or poured. [S3] Its FAQ names toothpaste, shampoo, conditioner, mouthwash and lotion as everyday items that must follow 3-1-1, and its item list adds liquid soap, peanut butter and hand sanitizer, each at 3.4 ounces or less. [S2] [S9]

Solid versions skip the bag. TSA’s item list allows bar soap and solid deodorant in carry-on bags without the liquids limit. [S9]

What are you packing?

Choose an item to highlight the line that applies.

Quart bag

Containers of 3.4 ounces (100 mL) or less go in your one quart-size bag. [S1] [S2]

Checked bag

A container over 3.4 ounces goes in checked baggage, however much is left inside. [S1]

No bag needed

Bar soap and solid deodorant are allowed in carry-on bags without the liquids limit, per TSA’s item list. [S9]

Declare it

TSA allows larger amounts of medically necessary liquids, gels and aerosols in reasonable quantities for your trip. Tell the officer at the start and put them in a separate bin. TSA says some contact lens solutions typically alarm and may not be allowed, so it suggests checking lens solution over 3.4 ounces. [S4] [S5] [S9]

Baby liquids

Formula, breast milk, toddler drinks and baby food, including puree pouches, are allowed over 3.4 ounces and don’t need to fit in the quart bag. Your child doesn’t have to be flying with you for you to bring breast milk. Take them out for separate screening. [S6] [S7]

Frozen solid

Frozen items, ice packs included, can go through if they are frozen solid at screening. Partly melted or slushy ones must meet 3-1-1. Medically necessary gel ice packs are the exception and are allowed melted or slushy; tell the officer. [S5] [S8]

Duty-free

On a trip to the US with a connecting flight, duty-free liquids over 3.4 ounces can stay in your carry-on if the shop sealed them in a clear tamper-evident bag that shows no tampering and you have the original receipt from within 48 hours. They still have to clear screening, and TSA recommends checking them anyway. [S1]

Empty bottle

An empty water bottle is fine in a carry-on. Fill it after screening. [S3] [S11]

Medicine and baby liquids: declare them

TSA’s rule page lists two exemptions: medications, and infant and child nourishment. [S1]

For medically necessary liquids, TSA allows larger amounts in reasonable quantities for your trip, but you have to declare them. Its medical screening page says to tell the officer before screening begins and to put them in a bin apart from your other things, along with accessories like freezer packs, IV bags, pumps and syringes. Officers may test them, and an item may not be allowed if an alarm can’t be resolved. [S4] [S5]

For babies and toddlers, formula, breast milk, toddler drinks and baby food are allowed over 3.4 ounces. Tell the officer at the start and take them out for separate screening. TSA suggests clear bottles where possible, since liquids in pouches or plastic bags may need other screening, and says you can ask for private screening at any point. For questions ahead of time, it suggests calling TSA Cares at (855) 787-2227 about 72 hours before you fly. [S6] [S7]

Packing the bag

Check each label. The size printed on the container is what counts, and 3.4 ounces or 100 milliliters is the most it can say. [S1]
Swap to solids where you can. Bar soap and solid deodorant stay out of the bag. [S9]
Fill one quart-size bag. TSA allows one per passenger. [S2]
Pack it where you can reach it. TSA says taking the bag out of your carry-on helps screening, unless your lane says otherwise. [S1] [S5]
Set medicine and baby liquids apart. Over 3.4 ounces, tell the officer before screening starts. [S5] [S7]
Bring the water bottle empty. Fill it once you’re through. [S3] [S11]

Packing the rest of the bag too? Our packing cubes guide explains the Eagle Creek Reveal XS/S/M set, and our power bank flight rules article covers the battery side of a carry-on.

Bag check

Every container in the bag says 3.4 oz (100 mL) or less.Everything fits in one quart-size bag.Full-size bottles are in the checked bag or staying home.Medicine and baby liquids over 3.4 oz are set apart to declare.Ice packs are frozen solid, unless they’re for medicine.The water bottle is empty.

Quick answers

Does a half-empty 6-ounce bottle count?

Yes. TSA’s limit is on the container, and it says containers larger than 3.4 ounces go in checked baggage. [S1]

Can I bring two quart bags?

No. TSA’s FAQ limits each passenger to one quart-size bag of liquids, gels and aerosols. Exempt items like medicine and baby liquids don’t have to fit in it. [S2] [S6]

Do I take the bag out in TSA PreCheck?

TSA’s medical screening page says you don’t need to remove 3-1-1 liquids in PreCheck lanes. In other lanes, follow the rule page and the officer’s instructions. [S1] [S5]

Is peanut butter a liquid?

For screening, it follows the same size limit. TSA’s item list allows peanut butter in carry-on bags at 3.4 ounces (100 mL) or less. [S9]

Are there limits in checked bags too?

The 3-1-1 rule is for carry-on bags. For aerosols and some other toiletries in checked bags, TSA’s item list cites an FAA cap of 2 kg (70 ounces) or 2 liters (68 fluid ounces) per person, with each container no larger than 0.5 kg (18 ounces) or 500 mL (17 fluid ounces). [S9]

Who has the final say?

The TSA officer at the checkpoint. TSA’s item pages say the final decision on whether an item is allowed rests with the officer. [S4] [S8] [S11]

Are products ranked here?

No. This guide explains TSA’s rule. It doesn’t rank or endorse any bottle, bag or toiletry, and no products were tested for it.

Sources

TSA pages checked October 22, 2026. Recommendations here are our editorial reading of those pages; no hands-on results are claimed.