The 3-1-1 liquids rule, explained properly
Complete breakdown of the TSA 3-1-1 liquids rule: 100 ml (3.4 oz) containers, quart clear bag rules, medical exemptions, and international rules.
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What counts as a liquid at airport security checkpoints?
Under federal screening protocols (49 CFR § 1540.111), any substance that can be poured, squeezed, spread, sprayed, or smeared is legally classified as a liquid, aerosol, or gel (LAG). This includes beverages, lotions, pastes, semi-solid foodstuffs (like peanut butter, Nutella, yogurt, hummus), and aerosol sprays. Solids such as bar soap, stick deodorant, and powder cosmetics remain unrestricted.
The checkpoint rule applies universally across TSA (United States), CATSA (Canada), and ICAO member states worldwide. The working regulatory test is physical consistency: if an item does not hold its independent shape at room temperature or flows under pressure, screeners must enforce container limits.
What official exemptions bypass the 3.4 oz container limit?
Medically necessary liquids, infant nutrition, and certified duty-free items are legally exempt from the 3.4 oz (100 ml) capacity limit and quart bag requirement. Passengers must verbally declare these items to screening officers prior to X-ray conveyor entry for dedicated secondary inspection (such as electromagnetic bottle screening or vapor trace testing).
Key statutory exemptions recognized by TSA and CATSA include:
- Prescription & OTC Medications: Liquid cough syrups, eye drops, injectable solutions (insulin, GLP-1s), saline IV fluids, and specialized nutritional formulas in quantities reasonably needed for the itinerary.
- Infant & Toddler Nutrition: Breast milk, infant formula, pasteurized juice, and pureed baby food pouches when traveling with an infant or toddler (or transporting milk home to a child).
- Cooling Ice Packs: Frozen or partially thawed gel packs and ice packs specifically used to chill declared medical supplies or infant milk.
- Duty-Free Purchases: Bottled liquids purchased past security or internationally, sealed in a certified Secure Tamper-Evident Bag (STEB) with an itemized receipt dated within 48 hours.
Liquid, Gel, and Aerosol Allowances Comparison Matrix
The following table summarizes cabin and cargo hold allowances across common liquid categories:
| Category | Carry-On Allowance | Checked Baggage Allowance | Checkpoint Action |
|---|---|---|---|
| Standard Toiletries | ≤ 3.4 oz (100 ml) in 1-qt bag | Permitted (FAA aggregate caps) | Standard X-ray lane |
| Medically Necessary Liquids | Exempt from 3.4 oz cap | Permitted (recommend cabin) | Must declare to TSO before bin |
| Infant Formula & Milk | Exempt from 3.4 oz cap | Permitted | Separate visual/vapor test |
| Spreadable Foods (Peanut Butter) | ≤ 3.4 oz (100 ml) only | Permitted | Confiscated if > 3.4 oz |
| Duty-Free Alcohol / Liquids | Exempt in sealed STEB (<48h) | Permitted (<70% ABV / 140 proof) | Optical bottle scan verification |
How should you pack liquids for frictionless security screening?
Pack your single clear quart-sized bag at the very top of your carry-on luggage or in an exterior zipped compartment for instant retrieval. Consolidate liquid products into reusable 100 ml leak-proof silicone bottles, replace liquid formulas with solid equivalents (such as shampoo bars, stick sunscreens, and toothpaste tablets), and place full-sized grooming products into checked luggage where FAA hazardous material quantity caps allow up to 2 liters (70 fl oz) aggregate per passenger.
Before heading to the airport, cross-check individual cosmetic and toiletry items using our Liquids Bag Checker Tool to ensure compliance with container capacity formulas.
How do airport 3D CT scanners affect liquid rules in 2026?
Computed Tomography (3D CT) checkpoint scanners allow security algorithms to rotate and analyze volumetric liquid densities, enabling passengers to leave 3-1-1 bags inside luggage at equipped lanes. However, despite trial lifting of volume limits at select European hubs, the standard 100 ml (3.4 oz) container restriction remains universally enforced across the United States, Canada, and the European Union.
Always pack to the universal 100 ml / 1-quart standard to prevent return-leg confiscations at airports operating legacy 2D X-ray systems.
Perguntas Frequentes (FAQ)
Frequently asked questions
Is deodorant considered a liquid by TSA?
Solid stick deodorant is completely exempt from liquid volume limits and flies unrestricted in carry-on bags. However, spray, gel, paste, and roll-on deodorants are classified as liquids and aerosols under 49 CFR § 1540.111 and must strictly adhere to the 3.4 oz (100 ml) container limit inside your single quart bag.
Does mascara count as a liquid under the 3-1-1 rule?
Yes. TSA, CATSA, and ICAO classify mascara, liquid eyeliner, lip gloss, liquid foundation, and cream cosmetics as liquids, aerosols, or gels (LAGs). Solid lipsticks, powder blushes, and solid makeup balms are exempt solids and travel without volume restrictions.
Is the 3.4 oz limit per individual container or total liquid volume?
The 3.4 oz (100 ml) limit applies per container, not to your total liquid volume. Every individual bottle, tube, or dispenser must have a manufacturer-printed capacity of 3.4 oz (100 ml) or less, and all containers must fit comfortably within one single clear quart-sized (1-liter) bag.
What happens if a 6 oz container is only half full?
Airport security officers will confiscate it. Transportation security regulations govern the marked container capacity, not the remaining liquid volume inside. A 6 oz (177 ml) bottle containing only 1 oz of lotion is legally non-compliant and will be rejected at the security checkpoint.
Are duty-free liquids allowed on domestic connecting flights?
Duty-free liquids exceeding 3.4 oz (100 ml) are permitted on connecting flights only if purchased internationally within 48 hours, sealed inside an intact Secure Tamper-Evident Bag (STEB), accompanied by an itemized receipt, and verified by checkpoint bottle scanners.