The 3-1-1 rule permits 3.4-ounce containers in one quart-size bag per person at the checkpoint.
What The 3-1-1 Rule Means In Practice
The liquid rule limits each container to 3.4 ounces (100 ml). All travel-size bottles need to fit in a single, clear, quart-size zip bag. One bag per flyer. Pack the bag on top so you can place it in the bin without fuss. Anything larger than travel size belongs in checked baggage unless it qualifies for an exemption described below.
Liquids cover more than shampoo. The rule also includes gels, aerosols, creams, and pastes. Think toothpaste, hair wax, hand sanitizer, sunscreen, face wash, and even soft foods that smear. If it spreads, sprays, pumps, or pours, treat it as a liquid at screening.
3.4 Ounces Liquid Rules For Carry-On
Here’s the short version: pack small containers in a quart bag, one bag per traveler. Keep the bag handy, and expect extra screening if something looks dense on the X-ray. If a bottle says 4 oz, it can’t ride in your personal item even when it’s half full. Screeners go by labeled capacity, not the current fill line.
Broad Guide To Common Items
This quick chart covers the items people bring most often and how the rule applies. When in doubt, check the agency’s searchable list before you leave for the airport.
| Item Type | Carry-On Limit | Checked Bag Notes |
|---|---|---|
| Toiletries (shampoo, lotion, gel) | Up to 3.4 oz each in one quart bag | No size limit; cap tightly to prevent leaks |
| Toothpaste & creams | 3.4 oz tubes or smaller | Any size allowed |
| Aerosol grooming (deodorant, hairspray) | 3.4 oz or smaller | Allowed; leave actuators on |
| Hand sanitizer | Follow current checkpoint rule; travel size unless stated otherwise | Any size allowed |
| Liquid cosmetics (foundation, setting spray) | 3.4 oz or smaller | Any size allowed |
| Food that spreads (peanut butter, hummus) | 3.4 oz or smaller | Any size allowed |
| Drinks from home | Not allowed above 3.4 oz | Any size allowed |
| Alcohol in bottles | Not in carry-on unless duty-free in STEB | Unopened under 70% ABV; quantity limits apply |
| Medically necessary liquids | Reasonable quantities allowed; declare at screening | Any size allowed |
| Baby needs (formula, breast milk, juice) | Reasonable quantities allowed; declare | Any size allowed |
How To Pack So Screening Goes Fast
Start with the quart bag. Use leakproof travel bottles for toiletries and label them. Place the bag in an outer pocket of your backpack or tote so it’s the first thing you pull out. Keep liquids grouped; don’t scatter mini bottles around your bag. If you carry a toiletry kit, stash the quart bag inside it and lift it out at the belt.
Next, split solid items from liquids. Solid deodorant, bar soap, and makeup sticks don’t need the quart bag. Powders over a large amount may get extra screening, so keep them in original packaging and move them to a tray if asked.
Traveling with hair tools that use small gas cartridges? Pack the tool with the safety cover on and check the airline rules. One small cartridge is typical for carry-on, and spares go in checked bags.
Exemptions That Allow Bigger Bottles
Some items can exceed 3.4 ounces in your carry-on. Declare them at the checkpoint and remove them from your bag. Officers may test a small sample or run extra scans. Pack them for easy access and give yourself a few spare minutes.
Medical Liquids And Gels
Items needed for health reasons can travel in quantities larger than travel size. This bucket includes liquid meds, contact-lens solution, CPAP distilled water, and gel packs used to keep meds cool. Put these in a separate pouch and tell the officer you have medical liquids before screening. For the official language and examples, see the agency’s page on medical items.
Infant And Toddler Feeding
Formula, breast milk, toddler drinks, and baby food pouches can exceed travel size. These items don’t need to fit in the quart bag. Expect the officer to swab the exterior of the container and ask you to open lids. The agency’s FAQ spells out the rule for breast milk, formula, and juice.
Duty-Free Purchases
Liquor and perfume bought airside can exceed travel size when sealed in a tamper-evident bag with a receipt. Keep the bag closed until your final stop. If you connect through another checkpoint, present the sealed bag to the officer. If the seal is broken, it may not pass screening.
Carry-On Versus Checked Bag
Carry-on gives you access mid-trip and reduces lost-bag risk. Checked bags let you bring family-size bottles, full-size sunscreen, and big aerosol cans that would be tossed at the belt. Large bottles ride in checked bags with caps taped and liquids inside leak pouches. Double-bag anything sticky or scented. Pressure changes can push fluid through loose caps, so give every lid a quarter-turn after you pack.
Alcohol has extra rules in checked luggage. Anything over 70% ABV is banned. Under that mark, you can bring unopened retail packaging within airline quantity limits. Glass breaks, so wrap bottles in soft clothes or a padded sleeve.
Mistakes That Slow You Down
Bringing a half-full 6-ounce bottle. Screeners go by the size on the label, not what’s left inside. Move the contents into a smaller container.
Forgetting the quart bag. Loose travel bottles floating in your tote will earn a manual search. Group them and you’ll be through faster.
Hiding oversized drinks. A large water bottle from home won’t clear the belt. Empty it before security and refill on the airside.
Mixing liquids with electronics. Keep your toiletry bag away from cables and battery packs. Dense layers can trigger extra scans.
Assuming an officer will bend the rule. Agents follow set screening limits. If you need a bigger size in the cabin, use the exemption paths above.
Nuances Travelers Ask About
Does A Solid Stick Need The Quart Bag?
No. Solid deodorant, lip balm sticks, bar soap, and stick foundation don’t go in the quart bag. They can live in your grooming kit or purse pocket.
What About Powders And Bath Salts?
Small powder containers stay in your bag. Large amounts may be screened separately. Keep lids tight and bring original labels when you can.
Are Spray Sunscreens Treated Like Liquids?
Yes. Sprays count as aerosols, so travel size only in the cabin. Large cans go in checked bags. As with any aerosol, protect the nozzle and pack near soft items.
Is Hand Sanitizer Still Treated Differently?
Travel size works at all checkpoints. If a larger temporary allowance is posted for a given period, the agency will publish it. When in doubt, stick to a small bottle in the quart bag.
Can I Bring Frozen Gel Packs?
Gel packs that keep meds or baby milk cold are fine. If they are partially melted as you reach the belt, the officer may treat them as liquids and test them. Keep them with the item they cool.
Reading Labels And Decoding Packaging
Look for the printed capacity, not just the shape. Travel size often reads 3 fl oz or 89 ml, which is under the limit. A few brands use 3.6 oz bottles; those won’t clear the belt. If a bottle lists only milliliters, 100 ml is the cap. Anything higher belongs in checked baggage.
Refillable silicone bottles are handy, but they stretch. Don’t overfill. Leave a small air gap so cabin pressure won’t force product out. Choose bottles with flip-caps that snap shut firmly. Screw-top jars leak less when you add a liner: cut a circle from plastic wrap, place it over the mouth, then close the lid.
Quick Decisions For Edge Cases
Use this table to settle tricky calls in seconds.
| Item | Cabin Rule | Tip |
|---|---|---|
| Peanut butter cup | Counts as liquid; travel size only | Pack snacks that don’t smear |
| Snow globe | Travel size only | Must fit in quart bag |
| Nail polish & remover | Travel size only | Remover has fumes; seal well |
| Perfume bottle | Travel size unless duty-free in STEB | Keep receipt with bag |
| Contact-lens solution | Allowed over travel size as medical | Declare at screening |
| Soup or yogurt | Travel size only | Buy airside if you want more |
| Ice pack half-melted | Treated as liquid | Freeze solid before you go |
| Aerosol dry shampoo | Travel size only | Protect the nozzle |
| Refillable bottles | Under 3.4 oz capacity | Leave headspace |
Step-By-Step Packing Plan
1) Lay Out What You Need
Pull everything you think you’ll use in a week: face wash, moisturizer, hair products, toothpaste, sunscreen, and a tiny perfume. Now cut it. Most trips need only two or three liquids besides toothpaste and sunscreen. Grab minis for the rest or go solid where you can.
2) Fill And Label
Use a small funnel and match like with like. Don’t mix brands in one bottle; if a reaction happens, you won’t know the cause. Mark each bottle with painter’s tape so you can swap labels later. Write the product name and the month you filled it.
3) Build The Quart Bag
Start with must-haves: toothpaste, face wash, sunscreen. Add hair gel or spray if you need it. Finish with moisturizer and a small hand cream. Stand bottles upright and press out extra air before you seal the zipper.
4) Pack For Screening
Place the quart bag in an outer pocket. Keep medical or baby items in a second pouch so you can present them quickly. If you bought duty-free, keep the sealed bag and receipt at the top of your carry-on.
Where To Check Official Rules
The agency keeps the current language here: Liquids, aerosols, and gels rule. For baby feeding items, this page covers the exemption: breast milk, formula, and juice. Rules can vary by country, so check local guidance if your trip includes non-U.S. airports.
Bottom Line For Smooth Screening
Think “small bottles in one bag,” and treat anything that pours or smears as a liquid. Use exemptions for health needs and baby feeding, declare them, and keep them separate. Buy drinks after security or keep duty-free sealed in the tamper-evident bag. Packed this way, you’ll move through the lane with less hassle and fewer repacks.