You can usually only take small amounts of liquids in your carry‑on on international flights, but there’s a lot more freedom with checked bags.

Core rule: carry‑on on international flights

For almost all international routes today, airports follow the “100 ml / 3.4 oz” rule for carry‑on liquids.

  • Each liquid container in hand luggage: max 100 ml (3.4 oz).
  • All your liquid containers must fit inside one clear, resealable bag of about 1 liter / 1 quart.
  • The bag must fully close; if it can’t zip, you’re over the limit.
  • This applies to liquids, gels, aerosols, creams, pastes, foams, and many cosmetics (shampoo, toothpaste, lotions, perfume, etc.).

This is what people mean when they talk about the “3‑1‑1” rule: 3.4‑oz bottles, 1 quart‑size bag, 1 bag per person.

Important exceptions (where you can exceed 100 ml)

Most countries allow some larger‑than‑100‑ml items in carry‑on if they’re essential, but they must be declared at security.

Common exceptions (check exact rules for each country):

  • Medications and medical liquids (including some liquid diet items), usually allowed in larger quantities if you show a prescription or doctor’s note when requested.
  • Baby food, formula, breast milk, and sterilized water for an infant traveling with you; many countries don’t set a strict ml cap but expect “reasonable” amounts for the journey.
  • Duty‑free liquids bought after security (in sealed tamper‑evident bags with receipt visible) are generally allowed even if over 100 ml, including on many international connections, as long as you don’t open the bag before your final screening.

A quick example: You can often bring a 750 ml duty‑free wine bottle through to your onward flight if it’s sealed in the official duty‑free bag with the receipt inside.

Differences by region (still mostly the same rule)

The broad pattern is similar almost everywhere for international flights:

  • US (TSA) – 3‑1‑1 rule: 100 ml / 3.4 oz containers, all in one quart‑size bag for carry‑on; checked baggage can hold more liquids but with limits for aerosols and flammables.
  • UK & EU – same 100 ml and 1‑liter‑bag rule for international flights; some UK airports are starting to use advanced scanners, but many still enforce 100 ml for now, especially if you’re connecting onward.
  • Canada, Australia, Japan, and many others – also use the 100 ml / 1‑liter‑bag standard for international travel, with similar medical and baby‑item exceptions.

If you’re starting at a “relaxed” airport (for example, some UK airports now allow up to 2 liters per container with new scanners), you still must plan for the strictest airport on your route , especially if you have connections. A connection through a country that still enforces 100 ml can mean your bigger bottles get confiscated.

How much liquid in checked baggage?

Checked baggage rules are more generous, especially for non‑flammable liquids:

  • Most ordinary liquids (like shampoo, regular drinks, sauces) can be packed in much larger bottles in your checked suitcase; the key concern is leak‑proof packing.
  • Flammable or pressurized items (aerosol sprays, some alcohol, etc.) often have total per‑person limits , e.g. a capped total volume of toiletry aerosols and limits on alcohol strength and quantity.

As a realistic scenario, checking a 1‑liter shampoo bottle or several full‑size toiletries is usually fine; carrying the same bottle in your hand luggage is not.

Simple packing strategy for international flights

To avoid losing items at security:

  1. Put all liquids and gels you need in‑flight (toothpaste, travel‑size shampoo, moisturizer) into 100 ml or smaller containers.
  2. Make sure they all fit into one 1‑quart/1‑liter clear zip bag.
  3. Pack anything larger (full‑size bottles, big drinks, large cosmetics) and anything uncertain into your checked baggage.
  4. Keep medications and baby items separate so you can show them to security if they exceed 100 ml.
  5. If you plan to buy duty‑free liquids , keep them in the sealed security bag with the receipt visible until your final destination.

Quick answer in one line

For most international flights, you can only take liquids in containers up to 100 ml (3.4 oz) each, all fitting into a single 1‑liter/1‑quart clear bag in your carry‑on , while much larger amounts are allowed in checked luggage.

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