Airline Carry-On Rules Explained: Liquids, Restrictions & What to Expect

Airline Carry-On Rules Don’t Have to Be Confusing

The boarding gate meltdown, we’ve all seen it. A traveller arrives confident, only to find their carry-on luggage doesn’t meet the airline’s rules, and they’re hit with a last-minute baggage fee. 

Packing for a flight can be tricky because airline carry-on rules vary by airline, airport and country. Along with size, something simple, like liquids, can often cause the most confusion. This article is a practical guide to help travellers avoid delays by checking bag size before they fly, preventing the confiscation of items at security and feeling confident rather than panicking at that stressful last-minute bag check.

Check your bag size against airline carry-on rules with our free CarryOK™ tool

What Are Airline Carry-On Rules?

Airline carry-on rules vary by airline and ticket type, but generally involve a main cabin bag (to go in the overhead compartment) and a personal item (like a small backpack or purse that fits under the seat), with some airlines applying weight limits. 

Bag Size (Carry-On Dimensions)

Most airlines allow one carry-on bag that fits in the overhead bin, plus a personal item that fits under the seat.

A typical carry-on size example is 22 x 14 x 9 inches (56 x 36 x 23 cm), including wheels and handles.

Personal items are usually smaller, such as a backpack, tote bag, laptop bag or purse.

Size limits vary by airline, especially on low-cost and international carriers.

Not sure if your bag fits? Use our CarryOK™ tool to check airline carry-on size rules.

Is there a weight limit for carry-on bags?

It depends on the airline.

• Many U.S. airlines do not set a weight limit
• Many international airlines limit carry-ons to 7–10 kg (15–22 lbs)

If your bag is overweight:

• Require you to check it
• Charge an extra fee
• Gate-check it at boarding

What items are allowed in a carry-on bag?

Most everyday travel essentials are allowed, as long as they meet security rules.

Commonly allowed items include:

• Clothing and shoes
• Electronics (phones, laptops, tablets, power banks)
• Medications and medical devices
• Travel documents (passport, ID, boarding pass)
• Liquids under 100 ml / 3.4 oz in a clear bag
• Snacks and empty water bottles (fill after security)
• Travel accessories like neck pillows and headphones

Prohibited items include sharp objects, weapons, flammable materials, and liquids over the allowed limit.

Here are some common TSA questions and answers about what you can and can’t pack. 

Carry-on rules help flights board faster and depart on time. Delays occur when bags that won’t fit in overhead bins or under a seat need to be gate-checked. Airline carry-on rules are designed to keep passengers safe, make the best use of cabin space and help flights depart on time.

Don’t be the one to cause the delay! Try CarryOK today!

What Are the Airline Rules for Liquids?

Liquids cause more confusion than almost anything else. Some airports allow liquids to stay in your bag, others require a clear plastic bag, some countries allow larger quantities, and others may confiscate even expensive perfume.

This confusion can lead to stress, delays, and items being thrown away.

So, what are the airline rules for liquids? Most airlines follow airport security regulations, which limit how much liquid you can bring in your carry-on.

Liquids Rules for U.S. Flights

For flights departing U.S. airports, liquids are subject to the TSA 3-1-1 rule:

• Containers must be 3.4 oz (100 ml) or less
• All liquids must fit in one clear, quart-size bag
• One bag per passenger

Items that count as liquids include:

• Toiletries
• Gels
• Creams
• Pastes
• Aerosols

Airline Liquids Rules for International Travel

Outside the U.S., liquid rules can vary by country and even by airport.

• Many UK and EU airports enforce a 100 ml limit
• Rules may differ depending on airport security scanner technology
• Duty-free liquids are often allowed if sealed properly
• Return flights may enforce different or stricter rules

Always check airport security rules, not just airline policies.

What Liquids Are Allowed in Carry-On Bags?

Allowed Under Airline Rules

• Toiletries under 100 ml
• Liquid makeup
• Small gels and creams

Exceptions to the Liquids Rules

• Baby formula and breast milk
• Prescription medications
• Medically necessary liquids (must be declared at screening)

Liquids That Must Go in Checked Bags

• Full-size toiletries
• Drinks and large aerosols
• Alcohol over permitted limits

Common Mistakes Travellers Make with Carry-On Liquids

• Bringing full-size containers
• Forgetting that gels and creams count as liquids
• Packing liquids deep inside the bag
• Assuming the rules are the same worldwide

Carry-On Bags & Unexpected Gate Checks

Even if you plan to carry your bag onboard, gate checks still happen, especially on full flights or on smaller aircraft.

That’s why:

• Carry-on bags may still end up in the cargo hold
• Locking your bag can help protect your belongings. For some helpful advice, look at Why You Should Always Consider Locking Your Carry-On
• TSA-accepted locks allow security to inspect bags without damage 

Learn more about how TSA-accepted locks work

Final Checklist: Airline Carry-On Rules Before You Fly

✔ Check airline size and weight limits
✔ Confirm what the airline’s rules for liquids are
✔ Pack liquids correctly
✔ Prepare for international differences
✔ Lock your bag responsibly

Use CarryOK™to check airline carry-on rules before you travel

Contact Travel Sentry for more Information

If you’re unsure about airline carry-on rules, liquid restrictions, or what to expect at airport security, Travel Sentry is here to help. 

Our resources are designed to make travelling simpler and less stressful, with clear guidance you can trust before you pack. Explore our advice or get in touch to learn more about travelling smarter and with peace of mind.

FAQs: Airline Carry-On Rules & Liquids

What are the airline rules for liquids in carry-on bags?

Liquids are usually limited to containers of 100 ml or less, packed in a clear bag, with exceptions for medical and baby items. These airline carry-on rules are enforced at airport security, so anything over the limit may be confiscated. Checking what are the airline rules for liquids before you travel can help you pack correctly and move through security with less hassle.

Do airline carry-on rules apply everywhere?

No. Rules vary by airport and country, even when flying with the same airline. Local security authorities can apply different standards, which means airline carry-on rules may change depending on where you’re travelling from or through.

Does toothpaste count as a liquid?

Yes. Toothpaste, gels, creams, and aerosols are all treated as liquids. These items must be included within your liquid allowance, so forgetting to pack them correctly can lead to delays or items being removed at security.

How can I check airline carry-on rules before flying?

Use Travel Sentry’s CarryOK™ tool to check carry-on size rules by airline. This makes it easier to confirm airline carry-on rules ahead of time and avoid unexpected issues at the airport, especially when flying internationally.