A one-litre bag does not hold a litre of toiletries. In practice it tends to hold six to eight small bottles, because the containers themselves eat the space and the bag still has to close properly. So the useful move is subtraction: work out which liquids come off the list before you start filling anything. The UK’s own guidance is blunt about the part most people miss: the carry-on liquids limit applies to the container, even when it is only part full.
That catches people twice. Once at the bottle, where a barely used 200 ml tube is still a 200 ml tube. Then again at the bag, because half of what fills it never felt like a liquid in the first place: toothpaste, sunscreen, mascara, the little pot of face cream. Both come down to one number, and it is printed on the outside of the bottle.
The Container Capacity Rule: Why Security Screeners Confiscate Half-Empty Bottles
Screeners confiscate half-empty bottles because the limit attaches to the container, not to what is left inside it. Brazil’s civil aviation regulator puts it in as many words: bottles over 100 ml cannot be carried, even when the bottle is only partly full. Manchester Airport’s guidance says the same thing for UK departures. A 200 ml bottle with a splash of shampoo in it is still a 200 ml bottle.
Both of those positions were checked on 20 September 2026, and both belong to a specific authority that can change them, which is why the airport you are flying from is the page to check before you pack, not a travel article. The rule also travels with the checkpoint rather than with you: none of these authorities set the limit by nationality, so at any given lane, everyone in the queue is under the same rule regardless of which passport they are holding.
The reason the rule is written this way is practical. A capacity is moulded or printed onto the vessel and can be read in a second at the belt. The quantity inside an opaque tube cannot be, and nobody is going to decant your conditioner into a measuring jug to settle the argument. So the enforceable number is the one on the outside. Canada’s screening authority writes that number two ways, 100 ml or 100 g, which matters for anything sold by weight.
What actually counts as a liquid
The container rule is the easy half. The half that empties people’s bags is deciding what counts as a liquid in the first place.
Work from what the thing does rather than from what it is called. Canada’s authority states one version of that test outright, though only for food: it counts as a solid if it is solid at room temperature, which is why freezing a jar of something does not convert it. For everything else you are reading the lists, and the lists are long.
The UK counts creams, lotions, oils, perfumes, mascara and lip gloss. The European Commission’s wording sweeps in gels, aerosols, pastes, lotions and liquid/solid mixtures. Canada’s list reaches as far as jam, yogurt, mashed potatoes, peanut butter and gel blush. Lisa Farbstein, formerly a spokesperson for the US Transportation Security Administration, gave the field version of this to Afar: if you can spill it, spray it, spread it, pump it or pour it, treat it as a liquid.
The table below covers the items that catch people out, rather than the obvious ones.
| What you are holding | Treated as a liquid? | What settles it |
|---|---|---|
| Toothpaste, shower gel, shaving foam | Yes | Pastes, gels and pressurised foams are named on the UK and Canadian lists |
| Mascara, liquid eyeliner, gel blush, lip gloss | Yes | Liquid- and gel-based cosmetics, named explicitly by both |
| Peanut butter, jam, yogurt, mashed potato | Yes | Spreadable food sits on Canada’s gel list |
| Bar soap, powder, solid stick deodorant | Not named on any of these lists | Absence from the list, rather than a rule saying solids are fine |
| Anything you froze to get around the rule | Yes, in the UK and Canada | Both refuse frozen liquids in hand baggage outright |
| A 150 g tube of something spreadable | Yes, in Canada | The limit there is written as 100 ml or 100 g |
The last column is the useful part. Two of those rows rest on an explicit rule and two rest on what the lists leave out, and that gap is where arguments at the tray start.
Where it gets decided is at the tray, not at your kitchen table. In a thread on r/HerOneBag, the person who started it described going through security in the UK and the Netherlands and being “really surprised when they took my solid deodorant and said it was a liquid”. Another traveller in the same discussion reported the same thing happening in Berlin, and being told that anything liquid at a warm temperature counts.
Those are two individual accounts from 2024 and earlier rather than a rate, but they mark a real seam. Solid sticks are not named as liquids on any list quoted here, and they are also not named as exempt, so the call belongs to whoever is working the lane.
The same thread carries a shortcut that circulates widely and is worth retiring: that millilitres on the label mean liquid and grams mean solid. Canada writing its limit as 100 ml or 100 g is exactly why that fails, and the table above has the consequence in a row of its own.
When an item genuinely sits on the line, look it up rather than argue it at the belt. The TSA publishes a searchable list covering thousands of specific items, and it states plainly that even a permitted item can be refused if it alarms during screening or if the officer has another concern. That is the honest boundary on everything in this section: the published rule tells you what should happen, and the officer in front of you decides what does.
How many compliant bottles you can actually fit into one bag is a separate problem, and it owes more to geometry than to regulation.
The One-Liter Pouch Math: Packing Geometry, Bag Dimensions, and Decanting Ratios
The bag’s stated capacity and its usable capacity are two different numbers, and the rules themselves say so. Brazil’s regulator requires the bottles to sit loosely inside the closed bag. The UK’s wording is that the contents “must fit comfortably inside the bag so it can be sealed”, and that the bag must not be tied at the top. Even the TSA’s guidance on miniature spirits turns on whether they “comfortably fit” into a single quart-sized bag. Three authorities, one idea: a bag stuffed to its theoretical volume is not a compliant bag.
Two other things eat the difference. Every bottle displaces more space than it holds, because the walls, the shoulder and the cap are not product. And the bag is a flat rectangle rather than a box: Canada puts a 1-litre bag at roughly 20 cm by 17.5 cm, the UK at approximately 20 cm by 20 cm. You are filling an outline, not a volume.
Then there is the unit itself, which quietly costs Americans room.
| The bag | Stated size | What that actually means |
|---|---|---|
| US quart bag | 1 US quart, about 0.95 litres | The smallest of the standard bags, by roughly 5% |
| UK, EU and Canada 1-litre bag | 1 litre | Flat, about 20 x 20 cm (UK) or 20 x 17.5 cm (Canada) |
| What you can genuinely fill | Less than either | The seal has to close with the bottles sitting loosely inside |
A quart is not a litre, and on a round trip the tighter of the two is the one that governs your packing. Pack to the litre for a European departure and you may be over on the way home through a US checkpoint.
The bag you bought may not be the bag you think
Retail toiletry pouches sold as compliant are not always compliant. On the Rick Steves travel forum, the traveller who opened the thread in November 2023 wrote that “many clear bags for flying exceed the 1 quart size”, and that some sold as quart-sized on retail sites were “nearly 2 quarts”. The solution that emerged from that discussion, repeated independently by several regular posters, was to stop buying a special bag and use a supermarket quart or litre freezer bag instead. Another poster explained what they had been told staff objected to at Heathrow at that time: unusual shapes and designs that made the contents hard to see, and bags that held more than they should.
Read that thread as a snapshot of late 2023, because the UK picture has moved a long way since. Heathrow no longer asks for a bag at all, and the UK government’s current position is that you do not have to use a separate transparent bag at every airport. What has not changed is the underlying test, and it is one you can run on your kitchen table. Put everything in, seal it, lay it flat and press gently: if the zip strains or the bag will not lie down, you are past the “fit comfortably” line the rules describe, and the fix is to remove something now rather than at the checkpoint.
One detail from Manchester Airport deserves more attention than it gets, because it defeats a lot of careful decanting. Its security guidance, last updated in April 2026, states that a container you bring yourself must have the capacity printed on it, that travel sets without printed measurements will not be allowed through, and that handwritten measurements and stickers are not acceptable. That is the container-capacity rule taken to its logical end: if there is no printed number, there is nothing for an officer to read, and the unreadable bottle fails for the same reason the oversized one does.
Which points at the real lever. Most people carry far more product than the trip needs, in bottles sized for the bathroom cabinet. Work out roughly how much of something you get through in a week, multiply by the length of the trip, and buy or fill to that, rather than defaulting to the largest compliant bottle.
In the same r/HerOneBag discussion, one traveller described decanting face products into contact lens cases, which she reckoned held at least five days’ worth. This is a rule of thumb built for this guide out of two things, your own weekly usage and the trip length, and not an industry standard. Do check the printed-capacity point above before relying on lens cases at a strict checkpoint.
If the honest answer is that your liquids will not fit no matter how you decant, that decision belongs to a different question, which is whether this trip should have a checked bag at all. That is the subject of our carry-on versus checked bag framework rather than this guide.
The Solid-Swap Strategy: Eliminating Bulky Liquids to Reclaim Pouch Space
Every gram you move out of the liquids bag buys space for something that cannot be swapped. Prescription skincare, liquid foundation, contact lens solution and a specific fragrance have no solid equivalent. Shampoo, conditioner, soap, deodorant and toothpaste mostly do, and they are also the bulkiest things in the bag. That asymmetry is the whole strategy: convert the heavy, replaceable items so the irreplaceable ones fit.
The mechanism is the one from the first section, running in your favour. Bars, sticks and powders are absent from the lists of liquids, aerosols and gels that the UK, the European Commission and Canada publish, so nothing about them is measured against the 100 ml ceiling and nothing about them competes for room in the bag. Canada makes the underlying principle explicit for food, where an item is a solid if it is solid at room temperature, and a shampoo bar behaves the same way in a warm bathroom.
| Liquid you are carrying | Solid equivalent | The honest trade-off |
|---|---|---|
| Shampoo and conditioner | Bars | Needs a tin or the bar softens and sticks to everything |
| Shower gel or body wash | Bar soap | Nothing lost, other than habit |
| Toothpaste | Tablets or powder | Texture takes a few days to get used to |
| Roll-on or gel deodorant | Solid stick | The one most often argued about at European checkpoints |
| Liquid foundation, serums, prescription creams | None that works | Keep these; they are what the reclaimed space is for |
The table’s last row is the point of the exercise. The swaps are not an end in themselves, they are how you stop choosing between your sunscreen and your medication.
Two cautions, because the internet oversells this. Solid does not mean invisible: powders draw their own attention, and the TSA requires powder-like substances over 350 ml or 12 oz to come out into a separate bin, while Heathrow states that powders over 350 g or 350 ml are not allowed in the cabin at all on flights to the United States.
And solid does not always mean accepted. The deodorant accounts in the r/HerOneBag thread are the worked example: two travellers describing a stick being treated as a liquid, at UK, Dutch and German checkpoints. A former British Airways crew member answering a similar question on Reddit reported never having a problem with a stick deodorant or a moisturiser bar in years of flying. Both things can be true, and the practical reading is that the swap works almost always and is not a guarantee, so the expensive version of a product is the wrong one to test it with.
That still leaves the items nobody should be swapping or shrinking, and those follow a different set of rules entirely.
Medical and Dietary Exemptions: How to Carry Necessary Liquids Outside the Pouch
Medically necessary liquids, baby milk and baby food are not squeezed into the bag. They travel outside it, in the quantity the journey requires, and every authority cited here says so in almost the same breath.
The TSA treats formula, breast milk and toddler food over 100 ml as medically necessary and states they do not need to fit within the quart-sized bag. The European Commission permits essential medicines, baby food and milk above 100 ml for use during the trip. The UK allows containers up to 2 litres through security at every UK airport for essential medical purposes, special dietary requirements, or baby food and milk. Brazil’s regulator permits prescribed liquid medicines in the quantity needed for the whole flight including stopovers.
All of those positions were checked on 20 September 2026.
What varies is the paperwork and the procedure, and that is where trips come unstuck.
On proof: Manchester requires a doctor’s letter, prescription copy or prescription label for liquid medication over 100 ml, and none at all for tablets or containers of 100 ml or less. Heathrow asks for a prescription or doctor’s letter only above 2 litres. Canada states that documentation is not required, while suggesting it may ease the process. Brazil requires a prescription, physical or digital, for the exemption to apply. These are four different answers to the same question, so carry the document if you have one and check the specific airport if you do not.
On procedure, the common thread is that you separate and declare before the bag goes into the machine, not after an officer finds something. The TSA asks you to inform the officer at the beginning of screening and remove the items to be screened separately, and it commits that screening will never involve putting anything into the liquid. If you would rather the item were not X-rayed or opened, you can say so and accept additional screening instead.
Brazil’s rules go further and give that right a name: under a 2015 directive you may ask the civil aviation security agent for a differentiated inspection without X-ray or metal detectors, handing the medicines over separately, and you may be asked to present, handle and repack them yourself so they are not contaminated.
Two practical limits are easy to miss. Heathrow states that breast milk must be in liquid form rather than frozen, should be in a clear container, and that metal or insulated containers are not permitted. And an exemption is permission to carry, not a guarantee of clearance: items that alarm still get resolved by the officer, the same as everything else.
Duty-free is the exemption people most often lose, and it is lost on a technicality rather than at the till. Canada’s authority is the clearest on how: purchases must be in an official sealed security bag with an itemised receipt, and you can be asked to surrender them if the retailer used the wrong bag, if the receipt is missing, if you opened the bag yourself, or if more than 48 hours have passed since purchase.
The same page warns that duty-free liquids “may be intercepted if you pass through pre-board screening at a connecting airport in another country or at multiple airports over a two-day period”. Manchester’s window is tighter still, at 24 hours. So the rule that survives everywhere is the narrow one: buy duty-free liquids on the last leg, keep the bag sealed until you are home, and treat any purchase made before a connection as a risk you are choosing.
None of these exemptions changes the thing that decides your packing, which is which checkpoint you will actually be standing at.
The 3D Scanner Patchwork: Why Connecting Flights Still Demand the 100 ml Standard
The headline that the 100 ml rule is dead is true at some airports and false at most, and the difference is decided gate by gate rather than country by country. Heathrow’s own guidance allows containers of up to 2 litres, left inside your cabin bag, across Terminals 2, 3, 4 and 5. Manchester, in the same country, still refuses anything over 100 ml. That is not a transitional wrinkle. It is the current state of play, checked on 20 September 2026.
Frankfurt shows how fine-grained this gets. Its security page explains that CT scanners are in use at most Terminal 1 checkpoints and all of Terminal 3, so 2 litres is allowed and no transparent bag is required. Then it lists where the old rules still apply: gates C1, C2, C4 and C6, certain special checkpoints, and transfer checkpoints for connecting passengers. At those lanes it is 100 ml containers in a 1-litre transparent bag. The airport’s own advice is to check your departure gate before you pack, which is the sharpest possible summary of the problem.
The comparison below is built from each airport’s and authority’s own published guidance, read on 20 September 2026. It is an analysis of what they publish, not a review of what happens on any given day.
| Where you are departing | Published container limit | What the relaxation does not cover |
|---|---|---|
| Heathrow (T2, T3, T4, T5) | Up to 2 litres, no bag needed | Heathrow warns that many other airports still apply 100 ml on your return |
| Frankfurt (most T1, all T3) | Up to 2 litres, no bag needed | Concourse C gates and transfer checkpoints remain at 100 ml in a 1-litre bag |
| Manchester | 100 ml, no bag required | The bag is gone, the container limit is not |
| Any US airport | 100 ml in one quart bag | Applies on arrival too, when you re-clear for a domestic connection |
| Dubai, Abu Dhabi | 100 ml | Standard limit at two of the largest connecting hubs outside Europe |
Every row in that table is a departure rule. That is the trap, and it is worth saying plainly: the generous airports create the risk, because the freedom is granted where you start and withdrawn where you continue.
Heathrow says so itself, in a note to outbound passengers that the same rules may not apply at the airport they fly home from. The UK government’s guidance is structured around the same instruction, telling travellers to check the rules at the airport they are flying from, at any airport they travel through, and on the return journey. Brazil’s regulator assigns that duty to someone else again, requiring the airline to tell passengers connecting in other countries whether the bag may be retained.
There is also a rumour worth closing off. In July 2025 the US Homeland Security Secretary suggested that container sizes could be the agency’s next announcement, and that comment has been recycled ever since. As of 20 September 2026 the TSA’s published rule is unchanged: 3.4 ounces or 100 ml per container, in a single quart-sized bag. CT scanners have been rolled out widely at US checkpoints, and what they change is whether the bag comes out of your luggage, not what may be in it. Anything sized on the strength of an announced change is sized on a rumour.
Which leaves one rule that works everywhere.
Security-compliant toiletry packing checklist
Run this once, the night before, against the whole itinerary rather than the first flight.
Step 1: Find the strictest checkpoint on the trip. List every airport you will clear security at, including the return and any connection where you leave the secure area. If any one of them enforces 100 ml, that is your limit for the whole trip.
Step 2: Sort by behaviour, not by label. Anything that spreads, sprays, pumps or pours goes in the liquids pile, including toothpaste, mascara and sunscreen. Anything that holds its shape at room temperature does not.
Step 3: Swap what can be swapped. Shampoo, conditioner, soap, deodorant and toothpaste out as solids. Keep the tin for the bars.
Step 4: Check every container for a printed capacity. Not handwritten, not a sticker. Unmarked decant bottles are refused at some airports.
Step 5: Size to the trip, not to the bottle. A week’s usage multiplied by the number of weeks, rather than the biggest compliant bottle you own.
Step 6: Set the exemptions aside, physically. Medicines, baby milk and baby food out of the main bag and reachable, with the prescription or doctor’s letter if the container is over 100 ml.
Step 7: Seal the bag and lay it flat. If the zip strains, remove something now.
Step 8: Leave duty-free liquids until the last leg. If you buy earlier, expect to lose them at a connection and decide whether that is acceptable.
The check that saves you the headache
The limit that governs your packing is not the one at the airport you are leaving from, it is the strictest one on your whole itinerary, including the leg home. So before you fill anything, list every checkpoint you will clear and look up the current rule for each one on that airport’s own site, because two airports in the same country now publish different answers and one of them may be a gate number rather than a terminal. Get that right and everything else here is bookkeeping. Get it wrong and the cost is rarely the shampoo, it is standing at a bin repacking a bag while the queue moves past you.
Frequently asked questions
What actually happens to liquids that do not clear security?
Canada’s screening authority lists three options: surrender them, move them to checked baggage if time allows, or ship them by mail or courier. Frankfurt adds a fourth, storing refused items in a sealed bag against a claim slip you redeem on your return.
Do I still have to take the liquids bag out of my luggage?
It depends on the checkpoint, not the country. Heathrow, Frankfurt’s scanner lanes and Manchester now let liquids stay in the bag, while the European Commission’s general guidance and Canada’s still require the transparent bag to go into a tray. Assume it comes out unless that specific airport says otherwise.
Are powders restricted in the same way?
They have their own rule. The TSA screens powder-like substances over 350 ml or 12 oz in a separate bin, and Heathrow states that powders over 350 g or 350 ml cannot go in the cabin on flights to the United States.
Travelling with children, do we get a bag each?
The UK, Canada and Brazil all write the allowance per passenger, and a child travelling with you is a passenger. None of them says whose luggage the bags sit in, and one traveller reported being asked to split two bags across two pieces of hand baggage, so keep them separate.
