In the US, TSA's 3-1-1 rule lets you carry liquids, gels, aerosols, creams and pastes in containers of 3.4 ounces (100 ml) or less, all fitting in one clear quart-size bag, one bag per passenger. Medications, baby formula and breast milk are allowed in larger amounts but must be declared at screening. Larger containers go in checked luggage. At airports with newer CT scanners you may not need to take the bag out, but the size limits still apply.
The liquids rule catches out more travelers at security than anything else. Here is how it works in the US.
The 3-1-1 rule
- 3.4 ounces (100 ml) or less per container.
- 1 clear, quart-size, resealable bag.
- 1 bag per passenger.
It applies to liquids, gels, aerosols, creams and pastes in your carry-on.
What counts as a liquid
If you can spread it, spray it, pump it, pour it or smear it, treat it as a liquid. That includes:
- Toiletries: shampoo, toothpaste, lotion, sunscreen, mouthwash
- Makeup: liquid foundation, mascara, lip gloss
- Food: yogurt, sauces, spreads, jam
- Drinks over 3.4 ounces (buy them after security)
Exemptions
Allowed in larger amounts, but declare them at screening:
- Prescription and over-the-counter medications
- Baby formula, breast milk and juice for infants
- Medically necessary liquids, such as contact lens solution
Duty-free liquids
Liquids bought in duty-free shops can usually travel in a sealed, tamper-evident bag with the receipt. On connecting flights, check the rules at your connecting airport.
Newer scanners
Many US airports now use CT scanners that let you keep liquids in your bag during screening. The size limits still apply unless official guidance changes. Follow the instructions at your checkpoint.
Packing tips
- Use refillable travel bottles of 3.4 oz or less.
- Choose solid toiletries (bar shampoo, solid deodorant, toothpaste tablets), which don’t count as liquids.
- Pack the liquids bag on top of your carry-on so it’s easy to reach.
- Put larger bottles in checked luggage, sealed in a zip bag in case of leaks.
Common questions
What does 3-1-1 stand for?
3.4-ounce (100 ml) containers, in 1 quart-size bag, 1 bag per passenger.
Can I bring a bigger bottle if it's only partly full?
No. The limit applies to the container's size, not how much is inside. A 6-ounce bottle with 2 ounces left isn't allowed.
Are medications and baby formula exempt?
Yes. Medically necessary liquids, baby formula, breast milk and juice for infants are allowed in reasonable quantities above 3.4 ounces. Tell the officer at screening; they may be tested.
Do the liquid rules apply on international flights?
Most countries use a similar 100 ml rule, but some airports with new scanners have relaxed it while others have not. Check the rules for each airport on your route.