TSA Liquid Rules in 2026: The 3-1-1 Rule Explained

The TSA 3-1-1 rule is simple to state. Every liquid in your carry-on has to be in a container of 3.4 ounces (100 milliliters) or less, all of those containers have to fit inside one quart-size resealable bag (about 1 liter), and you get one bag per passenger. At the checkpoint, you pull the bag out of your carry-on and set it in a bin so it can be screened on its own. Anything in a bigger container goes in your checked bag.

The name is a memory aid: 3.4 ounces, 1 bag, 1 passenger. The rule covers more than drinks, because TSA counts aerosols, gels, creams, and pastes as liquids too. A few categories are exempt, including medications and baby formula, which can go over the 3.4 oz limit if you declare them. And there is one 2026 wrinkle worth knowing: newer CT scanners at some checkpoints now let travelers leave liquids in the bag, but the 3-1-1 limits still apply, so pack to them every time.

Quick reference: the 3-1-1 rule at a glance

What is the TSA 3-1-1 rule?

It is TSA’s cap on the liquids you can carry through a security checkpoint and into the cabin. In TSA’s own words, you are allowed to bring a quart-size bag of liquids, aerosols, gels, creams, and pastes in your carry-on, limited to travel-size containers that are 3.4 ounces (100 milliliters) or less per item. Containers larger than that go in checked baggage.

The “3-1-1” shorthand breaks down as 3.4 ounces per container, one quart-size bag, one bag per passenger. Putting the bag in a bin and separating it from the rest of your carry-on is what speeds up screening, which is why officers ask you to take it out even when the line is moving fast. Anything that alarms during screening, liquid or not, gets additional screening, so a leaking or oversized container is the kind of thing that slows you and the line down.

How many ounces of liquid can you bring on a plane?

In a carry-on, the answer is 3.4 ounces (100 milliliters) per container, and the real limit is the bag. TSA does not publish a separate total-ounce number. As long as each container is 3.4 oz (100 ml) or less and they all fit in one quart-size resealable bag that still closes, you are within the rule. For most people that works out to roughly six to nine travel-size bottles.

One detail trips people up constantly: the size that counts is the size of the container, not how much liquid is inside. A 6 oz (177 ml) bottle with a single ounce left in it is still a 6 oz container, and it will not pass. Decant into proper 3.4 oz (100 ml) travel bottles, or buy travel sizes, and you avoid the most common reason liquids get pulled at the checkpoint. In checked baggage, the 3.4 oz limit does not apply at all, so full-size liquids belong there.

What counts as a liquid (gels, aerosols, pastes)?

This is where the rule surprises people. TSA’s definition is liquids, aerosols, gels, creams, and pastes, which sweeps in a lot of things you might not think of as a liquid. Toothpaste and peanut butter are the classic examples, both treated as falling under 3-1-1. So are mascara and lip gloss, sunscreen, hummus and yogurt, gel or aerosol deodorant, shaving cream, perfume, and similar items.

The practical test is whether you can pour, pump, squeeze, spread, or spray it. If you can, TSA treats it as a liquid and the 3.4 oz (100 ml) limit applies. Things that are genuinely solid are fine in any size: a bar of soap, solid stick deodorant, a sandwich, snacks. Powders are not liquids, but a powder-like substance over about 12 oz (350 ml) can trigger extra screening, so keep large powders accessible.

Exemptions: medications, baby formula, breast milk

Some liquids are too important to cap at 3.4 oz, and TSA exempts them. Medications, baby formula, breast milk, baby food, and other medically necessary liquids are allowed in your carry-on in reasonable quantities, even above 3.4 oz (100 ml), and they do not have to go in the quart bag.

The trade-off is a small extra step. Declare these items to the officer at the start of screening, take them out of your bag, and expect additional screening, which can include opening or testing the containers. You do not need to be traveling with a child to carry breast milk or formula. Ice packs, freezer packs, and gel packs used to keep medication, formula, or breast milk cold are covered by the same exemption. If you rely on a liquid medication, keep it separate and easy to reach so you can pull it out and mention it without holding up the line.

Liquids in checked bags and duty-free

Anything over 3.4 oz (100 ml) goes in your checked bag, where TSA sets no size limit on liquids. That is the home for full-size shampoo, lotion, sunscreen, and that jar of peanut butter. The limits that do exist on checked liquids come from the airline and from hazardous-materials rules, things like caps on aerosols and on how much alcohol you can pack, not from 3-1-1. Seal anything that might leak, because checked bags take a beating.

Duty-free is the one place liquids over 3.4 oz (100 ml) can ride in a carry-on, and only under strict conditions. On an international flight connecting through the United States, TSA lets you carry duty-free liquids over the limit if they were bought internationally, sealed by the retailer in a transparent, tamper-evident bag (a STEB) that shows no signs of tampering, and accompanied by the original receipt dated within 48 hours. The contents still have to clear screening, and anything that alarms or cannot be screened will not be allowed through. If you have a choice, TSA recommends packing those duty-free liquids in checked baggage anyway.

How the rule compares abroad

If you connect through Europe or the UK, the limit is effectively the same: 100 ml per container in a clear, resealable bag of roughly 1 liter. Some airports have installed next-generation CT scanners and at times relaxed the 100 ml rule, then reinstated it, so the limit has been inconsistent at a few European hubs. Treat 100 ml as the safe assumption for any international checkpoint, the same number as TSA’s 3.4 oz, and check your specific departure airport if you are counting on a higher allowance.

The bottom line

Pack to 3-1-1 and you clear the checkpoint without drama: containers of 3.4 oz (100 ml) or less, one quart-size bag, one per passenger, out of your carry-on and into a bin. Send everything bigger in your checked bag. Keep medications and baby formula separate so you can declare them. The CT scanners showing up at some airports may let you leave the bag packed, but the limits behind the rule have not changed, so the smart move is to pack as if every lane is the old kind.

Related guides

• Sorting out the bag itself? Check whether yours fits with the carry-on size checker.
• For a short trip, the weekend getaway packing essentials guide pairs a 3-1-1 liquids bag with the rest of a carry-on kit.
• Traveling for work? The business trip packing essentials guide covers toiletries and liquids for a carry-on-only trip.

Sources and methodology

The 3-1-1 rule, the 3.4 oz (100 ml) container limit, the quart-size bag, the bin-screening step, the exemptions for medications and infant and child nourishments, and the inbound-international duty-free conditions are taken directly from TSA’s official “Liquids, Aerosols, and Gels Rule” page (tsa.gov), verified June 27, 2026. The official page returned an HTTP 403 to a direct fetch, so the text was confirmed via a browser session against the live page. The detail that exempt items can exceed 3.4 oz in reasonable quantities and must be declared and additionally screened reflects TSA’s medications and traveling-with-children guidance linked from that page. The list of specific example items (toothpaste, peanut butter, mascara, and so on) and the “pour, pump, squeeze, spread, spray” test are editorial illustrations of TSA’s liquids/aerosols/gels/creams/pastes definition. The EU and UK 100 ml equivalence is stated at a general level. Always confirm current rules with TSA or your departure airport before you fly, because checkpoint technology and enforcement are changing.