The 3-1-1 liquids rule, explained properly
Guide · Liquids
On this page · 5 sections
3 — containers of 3.4 oz (100 ml) or less. 1 — they all fit in one quart-size (≈1 liter), clear, resealable bag. 1 — one bag per passenger. That is the entire rule, and everything else you have heard is a consequence or an exception of it. It applies at TSA checkpoints in the US, CATSA checkpoints in Canada, and under near-identical ICAO rules at most airports worldwide.
What actually counts as a liquid
The working definition at screening: if you can pour it, spread it, squeeze it, spray it, or smear it, it is a liquid. That sweeps in the obvious (shampoo, perfume, drinks) and the surprises — peanut butter, Nutella & hazelnut spread, yogurt, hummus, salsa, mascara, lip gloss, toothpaste, gel deodorant, snow globes, and soft cheeses. Solids are exempt: stick deodorant, lipstick, solid perfume, bar soap, wet wipes, and powder makeup all travel free of the rule. The label size on the container decides — a mostly empty 12 oz lotion is still a 12 oz container.
The exceptions worth memorizing
- Medication: medically necessary liquids (including cough syrup, contact solution in reasonable quantity, and injectables) may exceed 3.4 oz. Declare them before screening; they go through separate inspection.
- Babies: formula, breast milk, and baby food are exempt in reasonable quantities when traveling with an infant — declare them, too. Cooling ice packs for both categories ride along legally.
- Duty-free: full-size liquid purchases stay legal through connections if sealed in the tamper-evident bag (STEB) with the receipt inside — typically valid 48 hours.
- Frozen solid: a liquid frozen completely solid at the checkpoint passes like a solid. Slushy does not.
- New CT scanners at some airports let you leave liquids in the bag — but the 3.4 oz limit itself still stands almost everywhere in 2026.
Packing strategy that survives the bin
One quart bag holds roughly six to nine travel containers depending on shape. Decant into a good 100 ml bottle set, swap liquids for solids where the format exists (shampoo bars, stick sunscreen, toothpaste tablets), and put anything full-size in checked luggage where the only real limits are the FAA’s aerosol/toiletry aggregate (2 L total, 0.5 L per container). Test any bottle with the checker below — it answers label size, not vibes.
Priority Liquid & Spreadable Items
Sources: TSA Liquids Rule · CATSA. Last verified 2026-07-30.