TSA Liquid Rules for Carry-On Bags (3-1-1 Rule Explained)

This guide covers ordinary liquid packing at US TSA checkpoints. Check the current exception and presentation instructions for your route; another country or airport may use different rules.

The useful way to remember it is container first, bag second, exemption third: each ordinary liquid container must be 100 ml / 3.4 oz or smaller, all containers must fit in one quart-sized bag, and medically necessary liquids are handled separately.

What the 3-1-1 Rule Means

The rule is named for its three key numbers:

3.4 oz (100 ml) — the maximum size of any individual liquid container you can bring through security in your carry-on.

1 quart-sized bag — ordinary liquid containers must fit together inside a single, clear, resealable quart-sized bag. A US quart is approximately 946 ml. Bag dimensions and product shapes vary; check the specified capacity and actual closed-bag fit rather than relying on a retail name or universal centimetre measurements.

1 bag per person — each passenger is allowed one quart-sized bag of liquids. You cannot pool two people's liquids into one bag.

Follow the actual TSA checkpoint instructions about separate presentation. Scanner lane procedures can differ; do not automatically apply one tray procedure to every lane.

What Counts as a Liquid?

The TSA defines "liquids" broadly. The rule applies to:

• Liquids — water, juice, coffee, alcohol, soup, sauces, dressings
• Gels — toothpaste, hair gel, face moisturizer, body lotion, aloe vera gel
• Aerosols — hairspray, deodorant spray, cooking spray, spray sunscreen
• Creams and pastes — foundation, mascara, peanut butter, hummus, jam
• Suspensions — snow globes, liquid glitter items

If you're unsure whether something counts, ask yourself: could it be used as a liquid or gel, even if it has a semi-solid consistency? If yes, it's subject to the rule. Peanut butter is a gel. Spreadable cheese is a gel. Mascara is a liquid.

What Does NOT Count as a Liquid

• Solid food (sandwiches, fruit, cheese blocks, chocolate bars, hard candy)
• Solid deodorant (not gel or spray)
• Solid sunscreen sticks
• Powder (dry shampoo powder, baby powder, protein powder — check separate current powder-screening instructions)
• Lip balm (solid stick form)
• Solid makeup (compact powder, blush, eye shadow)

When in doubt, a good rule: if it pours, pumps, sprays, or squeezes, it's a liquid under the TSA's definition.

The 100 ml Container Limit

The limit applies to container size, not content. A 200 ml bottle that is half-empty is not allowed through security — the container itself must be 100 ml or smaller.

For the ordinary container-capacity check, rather than complete item approval:

• A 100 ml bottle filled to the brim: allowed
• A 500 ml bottle that's 80% empty: not allowed
• A 3.4 oz (100 ml) travel-size shampoo: allowed
• A full-size 250 ml conditioner: not allowed, even if you only packed it because it was 40% full

For products whose manufacturer permits repacking, use suitable labelled travel containers. Do not assume an unlabelled refill preserves medicine identification or the storage requirements of the original product.

The Quart-Sized Bag Requirement

All your 100 ml containers must fit together inside a single transparent, resealable bag approximately one quart (946 ml) in volume. The bag must:

• Be clear (transparent) — not opaque or tinted
• Be resealable (zip-top) — not a twist-top or open bag
• Keep ordinary liquid containers together; follow the checkpoint’s tray instructions

Test your actual containers in the closed quart-sized bag. Their combined liquid volume does not establish physical fit, and no fixed number of 100ml containers is guaranteed.

Use a clear resealable quart-sized bag matching the current TSA instructions. Retail wording such as “TSA approved” does not certify a whole bag or guarantee acceptance.

Medicines, infant supplies and duty-free

Check TSA’s current instructions for medically necessary liquids, infant supplies and their cooling materials before departure. Declare the identified exception and follow staff screening instructions. Do not treat ordinary supplements as automatically exempt or assume a partially melted medical cooling pack must fit the ordinary 100ml rule. Keep product identification and any required travel documentation available; security clearance does not establish medicine import permission.

For a second checkpoint, verify the applicable duty-free conditions before purchase. EU guidance keeps the item and receipt sealed until the final destination; if staff open it, tell them about onward screening for resealing. Use the transit guide. This is a scoped EU example, not full current TSA international-inbound exemption certification.

Practical Packing Tips

Build a dedicated liquid kit. Keep a pre-assembled quart-size bag with your travel toiletries — mini shampoo, conditioner, toothpaste, face wash, sunscreen, and hand lotion — ready to go. Repack and replace items as they run out. This saves repacking time before every trip.

Check refill compatibility. Use labelled containers only when suitable for the actual product. A silicone bottle is not automatically compatible with every formula or medicine; follow the manufacturer’s packaging and storage instructions.

Distinguish product forms. A genuinely solid bar or stick differs from a gel, cream or spray. This distinction does not approve every solid product or quantity; other transport, customs and product-use requirements remain separate. Handle any necessary medicine exception under its own instructions.

Put the liquid bag on top. Pack your quart bag last so it's accessible at the top of your carry-on when you approach the security checkpoint. Rooting through a packed bag at the belt wastes time and creates stress.

Don't rely on "consuming it before the checkpoint." TSA lines move unpredictably. A full water bottle you planned to drink in the queue may still be full when you reach the X-ray. Either finish it well before security or surrender it.

Know your connecting airports. If you're flying from the US to Europe via a hub, you'll clear security once in the US and may clear again in the hub. Check the European airport’s actual rule separately, including Heathrow’s current local exception. Don't assume a duty-free purchase in one country clears security in another.

International checkpoints are separate

The European Commission’s general EU-departure guidance uses 100ml containers in one transparent resealable bag of at most 1 litre, with trip-needed medicine and baby food/milk exceptions. A US quart is approximately 946ml, so it is not exactly a litre and is not the larger bag. Do not infer different enforcement tolerance from the unit.

Heathrow currently allows containers up to 2 litres each and liquids/large electronics to remain in the cabin bag. Empty metal and insulated bottles before its checkpoint. Other departure, transit and return airports require their own current check; a worldwide 100ml or universal shoes-off instruction is unsupported.

FAA’s personal-toiletry transport limit is separate from checkpoint screening: qualifying articles are limited to 2kg/2 litres combined per person and 0.5kg/500ml per container, with protected aerosol nozzles. Its page also notes the US TSA 100ml container limit. Consult TSA’s current liquid instructions for exception details and your lane’s procedure; the EU examples above do not establish US exceptions.