Guide · Packing

The 100ml Carry-On Liquid Rule: What You Can and Can't Bring

The little clear bag of tiny bottles is one of the most recognisable parts of modern flying — and one of the most misunderstood. Here is what the 100ml liquid rule actually covers, what counts as a liquid, what is exempt, and how to get through security without surrendering your sunscreen.

What the 100ml rule says

The commonly applied rule limits liquids in carry-on baggage to containers that each hold 100 millilitres (about 3.4 fluid ounces) or less. Those containers must fit comfortably into a single, transparent, resealable plastic bag — typically one litre in size — and each passenger usually gets one such bag. This is often summarised as the "3-1-1" rule: 100ml containers, one bag, one bag per person.

The limit is on the container size, not the amount inside. A 200ml bottle that is half empty still fails the rule, because the bottle itself is larger than 100ml.

What counts as a liquid

"Liquid" is broader than it sounds. For security purposes it includes:

• Water, juice, and other drinks.
• Gels — toothpaste, hair gel, hand sanitiser.
• Pastes and creams — sunscreen, moisturiser, face cream.
• Aerosols — deodorant, hairspray (small cans).
• Spreadable foods — jam, honey, yoghurt, soft cheese.
• Semi-liquids — mascara, liquid foundation, contact lens solution.

A simple test: if it pours, squeezes, spreads, or sprays, treat it as a liquid.

Exemptions: medicines, baby items, and duty-free

Some liquids are exempt from the 100ml cap, though they usually must be declared and screened separately:

• Essential medicines in quantities larger than 100ml — carry a prescription or doctor's letter where possible.
• Baby food, milk, and sterilised water in quantities needed for the journey.
• Duty-free liquids bought at the airport or on board, provided they are in a sealed security tamper-evident bag with the receipt visible.

Exemptions are handled at the discretion of security staff and vary by airport, so confirm the policy at your departure airport if you rely on one.

Are the rules changing?

Some airports have installed advanced CT scanners that, in future, could allow larger liquids through. But the rollout is uneven, the 100ml limit remains in force at most airports, and rules can change quickly — sometimes overnight. Never assume a larger liquid will pass just because it did at a different airport last year.

A worked example

You are packing for a weekend trip and want to bring a full-size 200ml sunscreen and a 150ml shampoo. Both fail the 100ml rule for carry-on even though neither is full. Your options: decant them into 100ml travel bottles for your clear bag, move them into a checked bag, or buy travel-size versions. Running the items through the Liquids Checker first tells you which approach you need before you reach the front of the security line.

Practical tips for a smooth security check

• Pre-pack your clear bag. Put all 100ml liquids in one resealable bag before you leave home.
• Decant, don't ditch. Reusable travel bottles save money and waste.
• Declare exemptions. Tell security about medicines and baby items before the scanner.
• Check your airport. Rules and scanner technology vary — confirm before you fly.

Frequently asked questions

This article is general travel guidance. Security rules for liquids vary by country and airport and can change quickly. Always confirm the current rule with your departure airport or the relevant official aviation security authority before you travel. Written by the PlanTrippr team and not sponsored by any third party.