TSA Liquid Limit: The 3-1-1 Rule (3.4 oz / 100 ml) Explained

The 3-1-1 rule, explained

The name is a memory aid: 3.4 oz containers, 1 quart bag, 1 bag per passenger. It applies only to carry-on bags and items on your person. Checked bags have no TSA liquid limit, although the FAA caps toiletries and aerosols at 70 oz (2 kg) per person, 18 oz (500 ml) per container.

The container size is what counts. A 6 oz bottle with 2 oz left in it will be taken; two 3.4 oz bottles of the same shampoo are fine if they fit in the bag.

What counts as a liquid?

TSA’s test: if you can spill, spread, spray, pump or pour it, it counts. That includes things people don’t think of as liquids: peanut butter, toothpaste, mascara, lip gloss, hummus, yogurt, gel ice packs that have thawed, snow globes and canned food.

Solid versions get you around the rule: stick deodorant, bar soap, shampoo bars, toothpaste tablets and solid perfume can be any size.

Common liquids: carry-on or checked?

Common liquids and where they can go
Item	Carry-on	Checked bag
Shampoo, conditioner, body wash	Limits3.4 oz (100 ml) bottles	Allowed
Sunscreen, lotion, moisturizer	Limits3.4 oz (100 ml) or less	Allowed
Toothpaste, gel deodorant	Limits3.4 oz (100 ml) or less	Allowed
Stick deodorant, bar soap, solid shampoo	AllowedSolids, any size	Allowed
Water and drinks	Limits3.4 oz, or empty bottle	Allowed
Prescription and OTC liquid medicine	AllowedOver 3.4 oz OK; declare it	Allowed
Formula, breast milk, baby food	AllowedOver 3.4 oz OK; declare it	Allowed
Contact lens solution	AllowedOver 3.4 oz OK as medical	Allowed
Aerosol hairspray, dry shampoo	Limits3.4 oz (100 ml) or less	AllowedUp to 18 oz per can

Exemptions: when you can bring more than 3.4 oz

Medication: prescription and over-the-counter liquid medicine in reasonable quantities. Keep it out of the quart bag and tell the officer.
Baby formula, breast milk, juice and baby food: reasonable quantities, with or without the child traveling. Ice packs to keep them cold are allowed.
Duty-free liquids bought abroad, when connecting in the US: sealed in the shop’s tamper-evident bag with a receipt from the last 48 hours.

Exempt liquids may get extra screening, such as a test strip or X-ray of the container.

CT scanners and PreCheck

At checkpoints with newer CT scanners, and in TSA PreCheck lanes, you may be told to leave your liquids bag and laptop in your carry-on. The 3.4 oz limit still applies; only the unpacking step changes.

Liquids rules in other countries

The EU, UK, Canada and most countries use the same 100 ml limit. Some UK and European airports with new scanners have allowed larger containers at times, but rules have changed back and forth, so pack for 100 ml unless your departure airport says otherwise. Coming home, remember the limit applies at every security checkpoint, including connections.

Frequently asked questions

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

Up to 3.4 oz (100 ml) per container in your carry-on, all fitting in one quart-size bag. There is no total-ounce limit other than what fits in the bag, roughly 7 to 10 small bottles.

What size is a quart-size bag for TSA?

A standard quart zip bag is about 7 × 8 in (18 × 20 cm), holding about 1 liter. It must be clear and close completely.

Is 100 ml the same as 3.4 oz?

Yes. 100 ml is 3.38 fluid ounces, which TSA rounds to 3.4 oz.

Can I bring a water bottle through TSA?

An empty one, yes, of any size. Fill it after security. A full bottle over 3.4 oz will be taken.

Do liquids in checked bags have a limit?

TSA sets no liquid limit for checked bags, but the FAA limits toiletries and aerosols to 70 oz (2 kg) per person and 18 oz (500 ml) per container, and alcohol over 70% ABV is banned.