You can generally fly with liquids in your carry-on baggage if each liquid container is no larger than 100 ml (about 3.4 ounces). All such containers must fit into a single, transparent, resealable plastic bag no larger than 1 liter (about a quart). This is the standard liquid limit for carry-ons in many places, including Europe and US TSA rules as of 2025. You are allowed only one such bag per passenger. Exceptions include medications, baby formula, breast milk, and duty-free liquids purchased after security, which may be allowed in larger quantities if declared and properly sealed. Some UK airports with new security scanners have eased the limit up to 2 liters per container, but this is still limited to specific airports. In checked luggage, there are generally fewer restrictions on liquid volumes. To summarize the common limits for liquids in carry-on luggage:

• Maximum container size: 100 ml (3.4 ounces) for each liquid container
• All containers must fit inside one transparent resealable bag of max 1 liter
• One bag per passenger
• Exceptions for medications, baby products, and duty-free liquids
• Some airports in the UK allow up to 2L per container with new scanners

This system is often called the "3-1-1" rule: 3.4 oz containers, 1 quart-size bag, 1 bag per passenger.