Cabin Liquids Checker (100 mL / 1 L bag)

Understanding the cabin liquids checker — concept and principle

Airport security in most countries limits the liquids, aerosols and gels (LAGs) you may carry through screening in hand luggage. Shampoo, toothpaste, lotion, perfume and drinks all count. Enter the sizes printed on your containers and this checker adds them up, flags any container larger than 100 mL and shows how much of a typical 1-litre bag your nominal volumes represent.

How it is calculated

You type the container sizes in millilitres, separated by commas or spaces. The checker:

1. Ignores blanks, zeros and non-numbers.
2. Counts the containers and adds their sizes: total = sum of sizes.
3. Lists every container over 100 mL, because each one must be 100 mL or less.
4. Compares the total with 1,000 mL and shows it as a rounded percentage: total ÷ 10 %.

The value to enter is the capacity printed on the container, not how much is left inside.

The principle

The common screening rule used in the EU, the UK, Korea and, as the TSA 3-1-1 rule, in the US, has two parts: each container may hold no more than 100 mL (3.4 oz in the US), and all of them must fit in one transparent, resealable plastic bag of about 1 litre (a quart-size bag in the US), one bag per passenger. The limit is on the container's capacity because security staff cannot measure how full a bottle is, so a half-empty 200 mL tube is refused even though it holds only 100 mL. Strictly, the second test is whether the bottles physically fit in the closed bag; the 1,000 mL comparison is a convenient approximation.

Worked example

1. Default input: 100, 50, 75, 30, 100.
2. Containers: 5. The largest is 100 mL, so each ≤ 100 mL: ✓.
3. Total: 100 + 50 + 75 + 30 + 100 = 355 mL.
4. Share of a 1 L bag: 355 ÷ 1,000 = 35.5%, rounded to about 36%.

How to read the result

A ✓ on both lines means the sizes meet the usual rule. Whether the bottles fit depends on their shapes: tall or rigid bottles take more room than their volume suggests, so close the bag at home to be sure. If a container is flagged, move it to checked baggage, buy a travel-size bottle or decant into a smaller one.

Common mistakes

• Thinking a partly used large bottle is acceptable because little is left.
• Forgetting that gels and pastes such as toothpaste, lip gloss, hair gel and peanut butter count as liquids.
• Packing the bag so full that it cannot be sealed.

Frequently asked questions

Can I take a half-full 200 mL bottle?

No. The container itself must be 100 mL or less.

Can I bring duty-free liquids on a connecting flight?

Usually only if they stay sealed in the shop's tamper-evident bag with the receipt, and transfer airports may still screen them. Check each airport on your route.

Is 3.4 oz exactly 100 mL?

3.4 US fl oz is about 100.55 mL; the TSA treats 3.4 oz and 100 mL as the same limit.

Sources: Commission Implementing Regulation (EU) 2015/1998, aviation security measures · U.S. Transportation Security Administration, liquids rule (3-1-1)