TSA 3-1-1 Liquids Rule — Complete 2026 Guide (With Exceptions)
The 3-1-1 rule trips up even experienced travelers. Here's exactly what it means, what's allowed, and what the TSA agents actually check for.
In This Guide
- 1. What the 3-1-1 Rule Actually Means
- 2. History: Why the Rule Was Created
- 3. What Counts as a "Liquid"
- 4. Complete List: Allowed vs. Not Allowed
- 5. Medical Exceptions: Medications, Baby Formula, Breast Milk
- 6. Duty-Free Liquids: The STEB Bag Exception
- 7. International Variations: EU, UK, and Beyond
- 8. Best TSA-Approved Toiletry Bags
- 9. Solid Alternatives: Beyond Liquid Toiletries
- 10. Getting Through Security Faster
- 11. What Happens If You're Flagged
- 12. The Smart Traveler's Pre-Security Checklist
- 13. FAQ: TSA Liquids Rule
What the 3-1-1 Rule Actually Means
The TSA's 3-1-1 liquids rule is one of the most misunderstood regulations in air travel, primarily because the name obscures what it actually means. Breaking it down: the first "3" refers to 3.4 fluid ounces (100 milliliters) — the maximum size of any single liquid container allowed in your carry-on. The "1" in the middle refers to one quart-size, clear, zip-top plastic bag. The final "1" means one bag per passenger, placed in the screening bin separately from your carry-on bag. Every number in the rule is a maximum, not a guideline: containers must be 3.4oz or smaller (not approximately), all containers must fit comfortably in the quart-size bag (not crammed in with the top partially open), and each passenger gets one bag — not one bag per person in your group sharing containers. The rule applies specifically to liquids, aerosols, gels, creams, and pastes in your carry-on bag. Items in your checked bag are not subject to the 3-1-1 rule. The 100ml container standard is based on FAA testing that determined this volume is insufficient to create dangerous quantities of liquid explosive when combined with other materials in a confined space — which is why the container size, not the aggregate liquid volume in your quart bag, is the critical constraint.
History: Why the Rule Was Created
The TSA 3-1-1 rule was implemented on August 10, 2006, in direct response to a disrupted terrorist plot known as Operation Overt — a UK-based plan to smuggle liquid explosive components onto multiple transatlantic flights and detonate them in flight. British intelligence, working with the CIA and Pakistani intelligence services, dismantled the plot before any flights were attacked, but the sophistication of the plan — which involved disguising bomb components as common beverages and personal care products — prompted immediate changes to international aviation security protocols. Within 24 hours of the arrests, the UK banned all liquids from aircraft cabins entirely. The United States implemented the more measured 3-1-1 system on the same day. The 3.4oz limit was not arbitrary: it was determined by security scientists to be the threshold below which available liquid quantities cannot be practically combined into a functional explosive device using the materials likely to be smuggled through an airport screening process. In the years since, TSA has periodically reviewed the rule, and in 2021 began testing CT scanning technology at select airports that can image liquids in carry-on bags without removing them — a technology that may eventually allow the 3-1-1 rule to be relaxed for passengers at equipped checkpoints.
What Counts as a "Liquid"
The definition of "liquid" under the TSA 3-1-1 rule is significantly broader than most travelers expect, and this expansive definition is the primary source of checkpoint confiscations for experienced travelers. The TSA applies the rule to liquids, aerosols, gels, creams, and pastes — which covers far more than the beverages and obvious toiletries most travelers think of. Items subject to the 3-1-1 rule include: shampoo, conditioner, and body wash; toothpaste and mouthwash (yes, toothpaste is a paste and subject to the rule); facial moisturizers, serums, and sunscreen; foundation, BB cream, and concealer; mascara and liquid eyeliner; lip gloss and liquid lipstick; hair gel, mousse, and pomade; shaving cream and shaving gel; contact lens solution; hand sanitizer; perfume and cologne; cooking spray (yes, even for camping); peanut butter (classified as a paste); hummus and other spreads; yogurt; soup in containers; honey and maple syrup; and any other product with a consistency between solid and liquid. Solid products are notably exempt: bar soap, shampoo bars, solid deodorant sticks, solid perfume, tooth tabs, and solid mascara bars all pass through without restriction. The practical takeaway: if you can pour it, squeeze it, smear it, or spray it, it's a liquid under TSA rules.
Complete List: Allowed vs. Not Allowed
Allowed in carry-on without restriction (not liquid, gel, cream, or paste): bar soap and solid shampoo, solid deodorant (not gel or spray), tooth tabs or tooth powder, dry shampoo powder, eyeshadow and pressed powder makeup, mascara in brush-only solid form, solid perfume and cologne, contact lenses in their original sealed packaging, solid snack foods (nuts, crackers, chocolate, whole fruits), gel shoe insoles inside shoes, and pens and markers. Allowed in carry-on under 3-1-1 rules (must be 3.4oz or less, in quart bag): all liquid toiletries in travel sizes, travel-size hand sanitizer (TSA has maintained a 12oz exception for hand sanitizer per passenger since 2020, verify current status before travel), liquid makeup, and all other liquids within size limits. Not allowed in carry-on regardless of size: alcoholic beverages over 140 proof, all compressed gas canisters including self-defense sprays, bear spray, gel-type shoe insoles sold separately, and anything classified as hazardous material regardless of volume. Subject to inspection and possible confiscation: any liquid container over 3.4oz even if mostly empty, any quart bag that doesn't fully close, and any liquid not in a container (loose ice packs that are not completely frozen). When in doubt before packing, the TSA website maintains an interactive A-to-Z list of items at tsa.gov/travel/security-screening/whatcanibring/all.
Medical Exceptions: Medications, Baby Formula, Breast Milk
The TSA's medical exemptions from the 3-1-1 rule are broader than most travelers know, and invoking them correctly can significantly reduce the toiletry restrictions for travelers with medical needs. Prescription medications in liquid form are exempt from the 3-1-1 rule regardless of container size, but they must be declared to TSA officers at the checkpoint and may be subject to additional screening. Over-the-counter liquid medications are also generally exempt when you inform the officer you're carrying them for medical necessity — this includes contact lens solution, medicated eye drops, and similar items. Baby formula, breast milk, and toddler juice or liquid food are specifically exempt from the 3-1-1 rule in reasonable quantities — there is no hard volume limit specified for these items, though TSA officers may screen them through additional testing. Parents should remove these items from the carry-on bag at the checkpoint and declare them separately. Travelers with medical conditions that require liquid nutrition, dialysis supplies, or other medically necessary liquids should contact TSA Cares (1-855-787-2227) before travel to arrange appropriate screening accommodations. Insulin and liquid medications for chronic conditions are explicitly exempt and should travel with any relevant prescription documentation. The practical advice for any medical liquid: declare it proactively, don't wait for the officer to find it in the bag, and carry any relevant documentation.
Duty-Free Liquids: The STEB Bag Exception
One frequently overlooked exception to the 3-1-1 rule involves duty-free purchases — specifically, alcohol and large liquid items purchased at airport duty-free shops after passing through security. These items are permitted in carry-on bags when they are: sold in a tamper-evident security bag (STEB), which is the sealed transparent bag provided by duty-free retailers; accompanied by a receipt showing purchase in the last 24 hours; and remain in the unopened, sealed STEB bag throughout the journey including any connecting flights. The STEB exception is where things get complicated on international itineraries: if you purchase duty-free at your departure airport, then connect through another country that inspects you at security before your connecting flight, the connecting security may confiscate your duty-free even in a STEB bag because they cannot verify the original purchase timestamp visually. This particularly affects travelers connecting through certain airports in the EU, UK, Canada, and Australia. If your routing involves a security re-screening at connection, the safest approach is to purchase duty-free at your last security-cleared airport before your final destination, not at the departure airport. The TSA website maintains current guidance on STEB exceptions, and duty-free retailers are generally well-informed about the rules affecting their products.
International Variations: EU, UK, and Beyond
While the TSA 3-1-1 rule applies to US airport security, international variations mean travelers need to check specific rules for each country they transit. The European Union follows the same 100ml / 1 liter bag standard as the United States — this is part of an internationally coordinated post-2006 aviation security protocol. However, EU airports have implemented CT scanning at many checkpoints that can image liquids without removing them from bags, meaning some airports no longer require removal of the quart bag for screening. The United Kingdom diverged from EU standards post-Brexit and maintained more restrictive measures, though as of 2026 the UK was in the process of implementing CT scanning at major airports that reduces the need for liquids removal. Japan follows the 100ml / 1 liter standard and is rigorously enforced — Japanese airport security is thorough and consistent. Australia and New Zealand follow the same international standard as the US. Canada follows the 100ml standard with the additional restriction that containers must meet the 100ml limit even if they're larger containers that are mostly empty — the container size, not the fill level, determines compliance. Travelers flying domestically within some countries encounter no liquid restrictions at all — domestic flights within several Asian and African countries do not apply liquids rules consistently. The smart approach for international travel: assume the standard 3-1-1 applies everywhere and be pleasantly surprised when it doesn't.
Pack Smart
The difference between a good trip and a great one often comes down to how organized your gear is before departure. The right accessories remove friction at every stage of travel — from security to hotel check-in to unpacking.
Best TSA-Approved Toiletry Bags
The quart-size bag requirement doesn't mandate a specific product — any quart-size, clear, zip-top bag meets the technical requirement. However, the generic grocery store bag approach causes problems: they tear after repeated security removals, they don't stand open at the checkpoint, and they look disorganized (which can prompt more scrutiny). Dedicated TSA-approved toiletry bags solve all these issues. What to look for: a clear bag that measures approximately 7 x 8 inches (the standard quart size), a sturdy zipper that doesn't separate under the weight of full containers, a flat profile that lies clearly for inspection, and enough rigidity to stand upright in a bin without flopping. The BAGSMART clear 2-pack reviewed in our travel bottles article exemplifies the type: durable zipper, correct dimensions, professional appearance that moves through security without comment. For travelers who carry a larger hanging toiletry bag, the optimal system is to have a dedicated TSA quart bag inside the hanging bag — all liquid items live in the quart bag permanently, so transfer to the security bin takes seconds instead of the fumbling excavation that slows the checkpoint for everyone behind you.
Solid Alternatives: Beyond Liquid Toiletries
The most elegant solution to the 3-1-1 rule is avoiding liquids altogether where alternatives exist — and solid alternatives for almost every liquid toiletry product now exist in mainstream retail. Shampoo bars have evolved significantly from their early, waxy incarnations. Modern shampoo bars from brands like Lush, Ethique, and HiBar lather generously, rinse clean, and leave hair feeling comparable to liquid shampoo. One shampoo bar typically provides 50-80 washes — enough for multiple trips — and takes up no liquid space. Solid conditioner bars are less common but increasingly available and work particularly well for fine hair. Toothpaste tablets have moved from specialty health food stores to mainstream retailers — Bite, Georganics, and similar brands offer tablet-form toothpaste that cleans effectively without TSA restriction. Solid perfume (available from nearly every fragrance brand) packs without restriction and often has better longevity than spray perfumes in the dry air of aircraft cabins. Solid sunscreen sticks (SPF 50+) are available from sport brands and provide TSA-free sun protection. Deodorant in solid stick form has always been TSA-exempt — a frequently forgotten benefit of traditional deodorant formats over gel or spray. Building a toiletry kit around solid alternatives can reduce or eliminate the quart bag entirely for some travelers, freeing that space in the carry-on for other items.
Getting Through Security Faster
Understanding how TSA agents check bags for liquid compliance tells you what matters for fast processing and what doesn't. X-ray operators are primarily looking for the density and shape of liquid containers — they're not reading labels. A 3oz bottle of water and a 3oz bottle of perfume look identical on X-ray, and both pass. What alerts the operator is container size: anything that appears larger than approximately 100ml in the scan gets flagged for manual inspection. The quart bag requirement exists for human inspection convenience, not X-ray detection — the liquids are visible in the X-ray regardless of whether they're in a quart bag. However, presenting a clearly packed quart bag that opens and lays flat is faster for the agent to visually clear than loose bottles that need to be repositioned and individually assessed. The fastest security move is preparation before the checkpoint: quart bag already removed from your carry-on, shoes and jacket ready to come off, laptop removed from bag (standard lanes), no metal in pockets. TSA PreCheck holders can leave laptops and liquids in bags — one of the most concrete benefits of the program for frequent travelers.
What Happens If You're Flagged
If a TSA agent flags a liquid in your carry-on, the process is straightforward and consistent: the agent will ask to inspect the item, verify the container size, and make a determination about whether it complies with the 3-1-1 rule. If the container is over 3.4oz, you have three options: check the bag at the counter (requires leaving the security area and re-entering), transfer the liquid to a compliant container at the security lane using the supplies some checkpoints provide, or surrender the item. Surrendering the item is the most common resolution for minor infractions — water bottles, that extra-large shampoo bottle, or the oversized moisturizer. For prescription medications or items you're claiming medical exemption for, the agent may call a supervisor for a secondary inspection. This takes 5-10 minutes and involves testing the item for explosive traces using a swab, then a supervisor review. Cooperate fully, declare the medical need proactively, and have any documentation available. The TSA is not looking for reasons to confiscate medical necessities — they are looking for explosive threats. Travelers who approach the process as cooperative rather than adversarial typically get through quickly even with legitimate medical liquids.
The Smart Traveler's Pre-Security Checklist
The five-minute check before leaving for the airport that prevents checkpoint surprises: First, verify every liquid container in your carry-on is 3.4oz or less — remove or pack in checked bag anything larger, even if it's mostly empty. Second, confirm all liquids are in your quart bag and the quart bag closes fully — the bag must close, not just be held shut. Third, put the quart bag in an easy-access location: the top of your carry-on or an exterior pocket. Fourth, check for liquids in unusual places — the water bottle in the side pocket, the travel-size perfume clipped to the bag exterior, the post-workout drink in the gym bag. Fifth, verify any items you're claiming exemptions for are documented and ready to declare. The traveler who moves fastest through a TSA checkpoint is the one who has done this checklist at home, not at the checkpoint. Checkpoint preparation is an act of consideration for every traveler in line behind you as much as it is efficient for you personally.
FAQ: TSA Liquids Rule
Q: Does the 3.4oz limit apply to the container size or how much liquid is in it? A: The container size — a 12oz bottle of shampoo that is 90% empty is still a 12oz container and not compliant. Q: Can I bring a 3.5oz or 4oz container if I tell the agent it's under 100ml inside? A: No. The container must be 3.4oz (100ml) or smaller — the volume of liquid inside is irrelevant to compliance. Q: Does hand sanitizer still get the 12oz exemption? A: The TSA granted a 12oz/one bottle per passenger hand sanitizer exception during the pandemic. Verify current status at tsa.gov before travel, as exemptions are periodically reviewed. Q: What if my liquids don't fit in one quart bag? A: You have too many liquids. Edit your toiletry kit, switch some products to solid alternatives, or move overflow to your checked bag. One quart bag is the limit. Q: Do I have to put my liquids in the bin separately from my bag? A: Yes — the quart bag must be removed from your carry-on and placed in the bin separately for X-ray inspection in standard screening lanes. TSA PreCheck does not require this.