Most passengers can bring only small liquid containers in their cabin bag, but the exact limit depends on where you’re flying from and the security technology at that airport.

Core rule most travelers must follow

For most airports worldwide (including many in the US and outside a few upgraded UK/European hubs), you still need to follow the classic “3-1-1” style rule for carry-ons.

  • Each liquid, gel, cream, paste or aerosol container: max 3.4 oz / 100 ml.
  • All containers must fit in one clear, resealable 1‑quart (≈1 liter) bag per passenger.
  • The bag must close comfortably (no forcing or overstuffing).
  • Anything larger than 100 ml in carry‑on is usually not allowed through security, even if the bottle is partly empty.

In checked baggage, these small limits generally do not apply to regular toiletries; you can pack larger bottles as long as they are not hazardous or flammable beyond airline rules.

New 2‑liter rule at some airports

In 2025–2026, several airports with new CT scanners have started removing the 100 ml rule for liquids in hand luggage.

  • At major UK airports like Heathrow, Gatwick, Edinburgh and Birmingham , you can now take liquids up to 2 liters per container in your cabin bag through security.
  • You don’t need to take liquids out of your bag at these upgraded checkpoints.
  • There is usually no limit on the number of containers , as long as each one is at or below 2 liters.

However, this is not yet universal :

  • Many other UK and European airports still enforce the 100 ml rule.
  • In the US , TSA is actively rolling out CT scanners, but the standard 3.4 oz / 100 ml, 1‑quart bag rule still applies at most airports in 2026 unless specifically stated otherwise.

Because rules differ, you might be allowed a big bottle on your outbound flight but not on your return if the other airport still uses the 100 ml system.

Exceptions to liquid limits

Most countries make similar exceptions, even where the 100 ml limit is enforced.

Common exceptions (usually allowed in “reasonable quantities”):

  • Medications (liquid, gel, or aerosol) that are necessary for your trip, often allowed above 100 ml but may need declaration or documentation.
  • Baby food and milk , formula, breast milk and sterilized water for infants.
  • Some special dietary liquids (e.g., for medical needs).

These often must be presented separately at security and may be screened with additional checks.

What counts as a “liquid”?

Security agencies treat many everyday items as liquids or gels.

Typically counted under liquid rules:

  • Drinks (water, juice, soda, alcohol).
  • Toiletries like shampoo, conditioner, lotion, liquid soap, hair gel, liquid makeup, mascara, liquid foundation, perfume.
  • Toothpaste, creams, pastes, gels (including hair gel), and many cosmetics.
  • Sprays and aerosols (deodorant, hairspray, spray sunscreen), with extra restrictions in some cases.

If it pours, squeezes, sprays, pumps, spreads, or smears, it is usually treated as a liquid or gel for security screening.

Quick checklist before you fly

Here’s a simple way to stay out of trouble at security:

  1. Check your departure airport’s rules
    • If it’s a CT‑scanner airport that has dropped the 100 ml limit (like some big UK hubs), you may be allowed up to 2‑liter containers in carry‑on.
 * Otherwise, assume the **100 ml, 1‑quart bag** rule still applies.
  1. Sort your liquids
    • Anything over 100 ml that isn’t clearly allowed by an exception should go in checked baggage, unless your airport explicitly offers the 2‑liter allowance.
  1. Keep exceptions handy
    • Medications, baby food or special‑diet liquids that exceed 100 ml should be accessible in your bag and, if possible, accompanied by a prescription or note.
  1. Think about your return flight and connections
    • If you buy duty‑free liquids, make sure they’re in official sealed bags and check whether connecting airports still enforce 100 ml limits.

TL;DR:

  • Standard rule at most airports: liquids in carry‑on must be in containers ≤ 3.4 oz / 100 ml , all fitting in one 1‑quart clear bag per person.
  • Some upgraded airports (like Heathrow and a few others) now allow up to 2 liters per liquid container in hand luggage, no plastic bag, thanks to new scanners.
  • Medications, baby items and essential dietary liquids often have special exceptions beyond these limits, but may be checked more closely.

Information gathered from public forums or data available on the internet and portrayed here.