Carry-On Liquid Rules Explained

The 100ml liquid rule (3.4 oz in the US) has been in place since 2006 and remains the global standard at nearly all airports. Promised technology that would eliminate the rule has been deployed at some airports but remains the exception. Pack assuming the rule applies.

The basic rule

Each container of liquid, gel, aerosol, paste, or cream must be 100ml or less. All containers must fit comfortably in a single transparent, resealable bag of approximately 1 liter capacity (the standard quart-size zip-lock bag in the US).

One bag per passenger. The bag must be presented separately at security screening.

What counts as a liquid

Anything that flows or can be poured: water, soda, juice, soup, alcoholic beverages.

Gels: hair gel, hand sanitizer, ointments.

Pastes: toothpaste, peanut butter, hummus, makeup foundation.

Creams: hand cream, sunscreen, makeup.

Aerosols: deodorant sprays, hairspray, sunscreen sprays.

Foods that look liquid: yogurt, applesauce, jam.

Common surprises

Mascara is technically a liquid and counts toward your bag. So is lip gloss, liquid foundation, and most other liquid cosmetics.

Snow globes and souvenir liquids over 100ml will be confiscated.

Frozen liquids: usually allowed if completely solid at screening time, but not if partially melted.

What is exempt

Baby formula, breast milk, and baby food: allowed in larger quantities for traveling parents. Inform the security officer at screening.

Prescription medications: allowed in any quantity. Bring documentation if quantities are unusually large.

Solid items: bar shampoo, solid deodorant, toothpaste tablets, lipstick (the bullet kind, not gloss).

Items purchased after security: drinks bought airside can be carried onto your flight, including water bottles purchased after security clearance.

Smart packing strategies

Use silicone travel bottles. Refillable from your full-sized products at home. More durable and reusable than disposable travel-size bottles.

Switch to solid alternatives. Bar shampoo, solid deodorant, toothpaste tablets, solid sunscreen all eliminate the liquid concern entirely. Lush and similar brands have a wide selection.

Buy at destination for bulky items. Sunscreen, lotion, larger toiletries are usually cheaper and more convenient to buy at your destination than to pack.

Use sample sizes for trial sizes. If you only need a few uses of something, the smallest sample size often suffices and saves space in your liquids bag.

If you are unsure

If you are not sure whether something counts as a liquid, pack it in checked luggage when possible, or be prepared to surrender it at security.

The TSA “What Can I Bring” tool answers most questions for US-bound travel. Other countries” aviation authorities have similar resources.

Newer technology at some airports

CT scanners (computed tomography) at some airports can scan liquids without removing them from your bag. Where deployed, you may not need to remove liquids during screening, and the 100ml rule sometimes does not apply.

Major airports with CT scanners include London Heathrow (full deployment expected by 2026), Amsterdam Schiphol, Rome Fiumicino, and progressively more US airports.

Until deployment is universal, assume the standard 100ml rule applies for any flight you book.