Last Updated on December 1, 2021
The 311 rule is an mnemonic used by the Transportation Security Administration to help you remember their rules about bringing liquids in carry-on luggage.
What Does The 3-1-1 Liquid Rule Mean?
The TSA wants you to remember 3 rules about bringing liquids in carry ons.
You need to know the 311 rule when you are taking liquids, gels, pastes, creams through the TSA checkpoint at airport security.
Each of the digits in the 3-1-1 represents one of the three TSA liquids limits that you need to know.
I bet you didn’t realise there are three limits!
Here is the meaning of the 3-1-1 rule.
Limit A – The Travel Size Containers Limit
This is the part of the 3-1-1 rule that everyone remember, even if they don’t remember the size of the bottles!
When you pack your carry-on bag any liquids, gels, or aerosols must be packed in bottles or containers that are 3.4 oz or less.
The reason that it’s 3.4 oz instead of 3 ounces is that 3.4 oz is equal to 100 ml.
There are some things that the TSA considers to be liquids that you might not. The TSA often says “If you can squeeze it, smear it, pump it, spread it, spray it, or spill it then it’s considered a liquid”.
So the 3 in the 311 rule represents the limit of 3.4 oz travel size bottles.
It’s the size of bottles that is important not the amount of liquid in them. So you can’t bring a 5 oz container that only has 3 oz of fluid inside it. The TSA officer will confiscate any oversize bottles even if they are half empty.
You can bring more than 3.4 oz of any particular liquid but it would need to be packed in two travel size containers.
Limit B – The Quart Sized Bag Rule
The first 1 in the 311 rule represents the fact that all your liquids must be packed in one quart size plastic bag.
This can be a simple resealable bag like a Ziploc or a more sturdy toiletries bag.
The TSA would prefer it if your bag is transparent so that your toiletries can easily be inspected by security officers but this isn’t mandatory.
You can usually fit 6 or 7 travel sized bottles in a quart size bag. That’s if you are playing by the rules.
Many travelers fly with ‘TSA Approved’ reusable toiletry bags that are not really TSA approved but can be as large as 2 quart.
The 3.4 container limit is strictly enforced but the ‘quart size’ part of the 311 rule isn’t as strictly enforced.
Limit C – Only One Liquids Bag Per Passenger
The last 1 in the 311 represents the fact that you are only allowed one plastic bag per person when going past security.
When you are in the security line take your one bag out and place it in a security bin to assist in the screening process.
It’s not one bag per suitcase. If you and a partner are sharing one carry-on bag you can bring two toiletries bags.
So we can now summarise the 3-1-1 rule.
- 3 – Your liquids must be in containers smaller than three point four ounces
- 1 – You must pack all liquids in a one quart size bag
- 1 – You are only permitted to bring one bag of liquids per passenger
There is a fourth limitation that is not represented in the 3-1-1 rule.
Limit D – No Flammable Liquids Unless They Are Toiletries
The type of liquid that you can pack is a further limitation but it’s not referenced in the 3-1-1 rule.
Travelers cannot pack any flammable or hazmat fluids in carry ons unless they are toiletries. You also can’t pack flammable liquids in your checked bag too.
Exemptions To The 311 Rule
Occasionally you are permitted to bring liquids in containers larger than 3.4 oz. These do not need to be packed in your quart size bag.
You can bring baby formula or breast milk in larger containers.
You can also bring milk, juice, yogurts, or liquid foods for infants in larger container sizes.
Take note, once a child can walk through the airport without the assistance of an adult they are no longer considered an infant by the TSA and the exemption ceases to apply.
You can also bring liquid medication in reasonable quantities though the airport security checkpoint.
Any oversize liquid will need additional screening. Place these items in a separate bin so the TSA agents can inspect them.
Keep in mind that the 3-1-1 liquids rule only applies to carry-on baggage. If you are packing liquids in checked bags you mainly just need to make sure they are not flammable although there is a limit for alcohol in checked bags.
The Bottom Line
The 311 liquids rule means passengers can only pack 3.4 oz or less containers in carry-on bags. You pack them all in 1 quart sized bag. And you are only permitted 1 bag per person.
Exemptions exist for medically necessary liquids and drinks for kids.
It’s as simple as that!