Traveling With Carry-Ons: Understanding Ounce Limits

When travelling with carry-on luggage, it is important to be aware of the restrictions on liquids, gels and aerosols. The rules vary depending on the country and airport, but in the United States, the Transportation Security Administration (TSA) enforces the 3-1-1 rule for carry-on luggage. This means that each passenger may carry liquids, gels and aerosols in travel-sized containers that are no more than 3.4 ounces (100 millilitres) each. These containers must fit into a single quart-sized bag. This rule applies to common travel items such as toothpaste, shampoo, conditioner, mouthwash and lotion. While this rule may seem inconvenient, it is an important safety measure to prevent dangerous substances from getting on planes.

The 3-1-1 liquids rule

• 3: Liquids must be in containers that are no larger than 3.4 ounces (100 millilitres) in volume.
• 1: All containers must fit into one quart-size clear plastic bag.
• 1: Only one plastic bag containing liquids is allowed per passenger.

This rule applies to common travel items such as toothpaste, shampoo, conditioner, mouthwash, and lotion. It is important to note that any liquid, aerosol, gel, cream, or paste that alarms during screening will require additional screening.

There are some exceptions to the 3-1-1 liquids rule. For example, medically necessary liquids, such as prescription medications, breast milk, and baby formula, are allowed in reasonable quantities and may exceed the 3.4-ounce limit. Additionally, duty-free liquids purchased internationally and transported in secure, tamper-evident bags are exempt from the rule when travelling to the United States with a connecting flight. However, the original receipt must be presented, and the liquid must not show signs of tampering.

Exceptions to the rule

The 3-1-1 rule, created by explosive experts, requires airline passengers to pack liquids inside 3.4-ounce containers that can fit into one quart-size bag. However, there are exceptions to this rule.

Medically Necessary Liquids

Medically necessary liquids are exempt from the 3-1-1 rule. This includes prescription liquids, gels, and aerosols, as well as liquid medications and contact lens solution. Prescription medication must be clearly labelled, and may be screened visually, with an x-ray machine, or with a vapor analysis. Liquid medications that are not prescriptions and contact lens solutions are limited to 3.4 ounces, but larger amounts of medically necessary liquids, gels, and aerosols are allowed in reasonable quantities for your trip, as long as they are declared to security officers first.

Infant and Child Nourishments

Breast milk, baby formula, baby and toddler food and drinks, and water for babies are all exempt from the 3-1-1 rule. TSA categorizes these as "medically necessary liquids," and the child does not need to be present for the exception. To expedite the screening process, TSA suggests using clear and translucent bottles, so they can be screened by Bottle Liquid Scanners.

Duty-Free Liquids

Duty-free liquids purchased internationally and transported in a secure, tamper-evident bag are exempt from the 3-1-1 rule when traveling to the United States with a connecting flight. The original receipt must be present, and the purchase must have been made within 48 hours.

Live Fish and Coral in Water

Live fish and coral in water are exempt from the 3-1-1 rule, as long as they are in a clear, transparent container and properly inspected by a TSA officer.

Biological Specimens

Non-infectious specimens in preservative solution, including formaldehyde, ethanol, isopropanol, or other alcohols, are exempt from the 3-1-1 rule if they are for scientific research. They must be packed with up to 30 milliliters of free liquid in a heat-sealed inner plastic bag, and no more than one liter in the outer packaging, which must be marked: "Scientific research specimens, 49 CFR 173.4b applies."

Liquids banned entirely

Liquids were almost entirely banned from hand luggage following a 2006 terror plot that saw terrorists attempting to smuggle explosives disguised as soft drinks onto flights. The incident, known as Operation Overt, was the largest terror plot ever discovered in Britain and resulted in a complete ban on liquids in hand luggage.

In the years since, the liquid ban has been relaxed in some countries, with the introduction of new computed tomography (CT) scanners at airport checkpoints. These machines use 3-D imaging to detect hazardous liquids, and have allowed some airports to eliminate liquid restrictions entirely. However, the roll-out of this new technology has been slow, and many airports still enforce the original liquid restrictions.

As of 2024, the Transportation Security Administration (TSA) in the United States still enforces the 3-1-1 rule for liquids in carry-on luggage. This rule allows travellers to carry liquids, gels, and aerosols in travel-size containers that are 3.4 ounces (100ml) or less. Each passenger is limited to one quart-size bag of liquids, and any larger containers must be packed in checked baggage.

While the liquid restrictions can be inconvenient for travellers, they are necessary to ensure the safety of passengers. Intelligence agencies continue to receive information indicating that terrorist groups are interested in targeting civilian aviation, and the liquid restrictions are an important safeguard against potential attacks.

Screening liquids

To ensure the safety of passengers, the Transportation Security Administration (TSA) has established guidelines for screening liquids, gels, and aerosols in carry-on luggage. The internationally recognised guideline is known as the 3-1-1 rule, which allows travellers to pack liquids in 3.4-ounce (100 ml) containers that collectively fit inside a one-quart-size , clear, plastic, zip-top bag. This bag should be easily accessible, preferably in the front pocket of your carry-on, for efficient screening.

The 3-1-1 rule covers a range of common travel items, including toothpaste, shampoo, conditioner, mouthwash, lotion, and face wash. Liquids that do not adhere to the 3-1-1 rule, such as those larger than 3.4 ounces, must be packed in checked luggage. However, there are exceptions for certain liquids that are considered medically necessary or purchased duty-free.

Medically necessary liquids, such as prescription medications, breast milk, baby formula, and liquid-filled teethers for infants, are allowed in reasonable quantities. It is recommended to declare these items to security officers and ensure proper labelling to avoid any issues during screening. Additionally, duty-free liquids purchased at the airport or on board an aircraft are permitted in secure, tamper-evident bags (STEB).

During the screening process, any liquid, aerosol, gel, cream, or paste that alarms the security system will require additional screening. This may include visual inspection, x-ray screening, or alternative testing methods. It is important to note that the final decision on whether an item is allowed through the checkpoint rests with the TSA officer.

While the 3-1-1 rule is still in effect, the TSA anticipates that the limit on liquids may be lifted in the coming years with the introduction of advanced 3-D imaging technology at airport checkpoints. In the meantime, travellers should adhere to the current guidelines and remain informed about any updates or changes to the liquid allowance for carry-on luggage.

Liquids in checked baggage

If you're travelling with liquids, you'll need to be aware of the restrictions on how much liquid you can carry on to your flight. The rules are clear: each passenger may carry liquids, gels, and aerosols in travel-sized containers that are no larger than 3.4 ounces (100ml). Each passenger is limited to one quart-size bag of these liquids. This includes items such as toothpaste, shampoo, conditioner, mouthwash, and lotion.

Now, for liquids in checked baggage, there are a few things to keep in mind. Firstly, it's important to research and identify any liquids that are prohibited on airplanes altogether. The Transportation Security Administration (TSA) provides a list of prohibited liquids on its website, and it's crucial to abide by these restrictions. Additionally, the Federal Aviation Administration's list of hazardous materials should be consulted to ensure compliance.

When it comes to packing liquids in your checked baggage, it's advisable to take precautions to avoid leaks and spills. Consider using leak-proof containers and double-bagging liquid items. Wrapping the tops of bottles or containers with duct tape can help keep the caps secure. Utilizing plastic bags, bubble wrap, or cardboard boxes can provide additional protection and absorption in case of leaks. It is also recommended to place liquid items in the centre of your suitcase, surrounded by clothing and other soft items to provide cushioning in case of impact.

Another important consideration is the destination-specific regulations regarding certain liquids. For instance, if you're travelling to or from Canada, it's worth reviewing the Canadian air travel regulations for any restrictions. Similarly, visitors to the United Kingdom should refer to their specific guidelines for items allowed in checked baggage. Keep in mind that coloured liquids, such as red wine or nail polish, pose a risk to your clothing and should be carefully considered.

Frequently asked questions