TSA Liquid Carry-On Rules: The Complete 3-1-1 Screening Guide (2026)

Table of Contents

• Deconstructing the TSA 3-1-1 Formula
• TSA Liquid Rules at a Glance (Limits & Container Specs)
• What Counts as a Liquid? Borderline Items Explained
• Medical, Infant, and Dietary Liquid Exemptions
• Duty-Free Liquids and Secure Tamper-Evident Bags (STEBs)
• Packing Strategy: How to Prevent Leaks & Speed Up Checkpoints
• Frequently Asked Questions

Deconstructing the TSA 3-1-1 Formula

Every commercial airline traveler passing through a United States Transportation Security Administration (TSA) checkpoint operates under Title 49 of the Code of Federal Regulations (see the official TSA liquids guidance). The rule is colloquially known as the 3-1-1 rule, and each digit corresponds to a concrete packaging parameter:

• 3: 3.4 fluid ounces (100 ml) or less per container. Crucial checkpoint rule: The restriction applies to the container capacity, not the remaining amount of liquid inside. A 6-ounce lotion bottle with only 1 ounce of product remaining will be confiscated at security.
• 1: 1 clear, quart-sized, zip-top plastic bag. The bag dimensions must not exceed approximately 7 inches by 8 inches. Standard slider bags or rigid clear toiletry pouches with durable zippers that match quart dimensions are accepted.
• 1: 1 bag per passenger. Each ticketed passenger, including children, is entitled to one quart bag in their carry-on or personal item bag.

Before packing your suitcase, make sure you coordinate your liquids kit with our curated list of essential TSA-approved travel items. Pairing compliant silicone refill bottles with a high-capacity bag from our guide to the best carry-on luggage ensures your baggage passes overhead bin and security checks without issue.

TSA Liquid Rules at a Glance (Limits & Container Specs)

What Counts as a Liquid? Borderline Items Explained

Travelers routinely lose valuable cosmetics and gourmet foods at security because TSA defines a “liquid” far more broadly than physical state chemistry. Under checkpoint screening protocols, the 3-1-1 rule covers liquids, gels, pastes, aerosols, creams, and spreads.

Common items subject to the 3.4-ounce limit that frequently catch passengers off guard include:

• Food spreads: Peanut butter, Nutella, hummus, jam, honey, creamy cheeses (brie, camembert), and salsa. Solid hard cheeses (cheddar, parmesan blocks) are completely unrestricted.
• Cosmetics: Liquid foundation, mascara, lip gloss, concealer pastes, setting sprays, and nail polish. Standard solid lipsticks and powder compacts are exempt and do not count toward your quart bag.
• Personal hygiene: Toothpaste, mouthwash, liquid roll-on deodorant, and shaving cream. Solid stick deodorant is exempt from the 3-1-1 bag. For grooming blades, check our detailed guide answering can you bring a razor on a plane.
• Gels & Ice packs: Gel shoe inserts, cold compresses, and reusable ice packs. Ice packs are only allowed through security if they are frozen completely solid when presented at the screening belt. If melted or slushy, they are seized.

Medical, Infant, and Dietary Liquid Exemptions

The TSA grants explicit exemptions for medically necessary liquids and infant nutrition. These items do not need to fit inside your 1-quart bag, and they can be packed in containers substantially larger than 3.4 fluid ounces.

Medically Necessary Liquids

You can carry reasonable quantities of the following prescription and over-the-counter liquids:

• Prescription cough syrups, antibiotics, and oral suspensions.
• Insulin vials, syringes, and related diabetes supplies.
• Saline solution and eye drops for contact lens care.
• Liquid nutritional supplements and feeding tube formulas for patients with medical conditions.
• External cooling ice packs or gel packs used specifically to preserve temperature-sensitive medications.

Screening Protocol: Remove these items from your carry-on luggage before the conveyor belt. Hand them directly to the screening officer and state, “I have medically necessary liquids to declare.” Officers will inspect the exterior of the containers, run paper strip vapor tests, or utilize bottle scanners.

Infant and Toddler Nutrition

Parents and caregivers traveling with infants or toddlers (generally defined as children aged 2 and under) may bring:

• Expressed breast milk (even if traveling without the infant).
• Prepared baby formula (liquid or powder format).
• Sterilized nursery water for mixing powdered formula.
• Pureed baby food pouches and jarred baby food.
• Frozen cooling packs used to maintain breast milk temperatures.

For the most current guidance on medically necessary liquids, breast milk, formula, and food for young children, consult TSA’s official What Can I Bring? directory before travel.

Duty-Free Liquids and Secure Tamper-Evident Bags (STEBs)

Passengers returning to the United States on connecting flights often purchase liquor, perfumes, or olive oil at international duty-free stores. If you have a domestic layover in the US, duty-free liquids exceeding 3.4 ounces are permitted in your carry-on only under strict conditions:

1. The liquid was purchased within the preceding 48 hours.
2. The retailer packed the item in a transparent, tamper-evident bag conforming to international STEB specifications.
3. The original receipt is visible inside the bag and matches the purchase timestamp.
4. The bottle passes non-destructive screening on the airport’s bottled liquid scanner.

If the tamper-evident seal is torn, punctured, or compromised, TSA officers cannot allow the bottle through security, forcing you to check the bag or abandon the bottle.

Packing Strategy: How to Prevent Leaks & Speed Up Checkpoints

Cabin pressure drops as aircraft climb to cruising altitude (equivalent to roughly 6,000 to 8,000 feet of elevation). This atmospheric pressure drop causes air pockets inside toiletry bottles to expand, forcing liquids out past threads and caps.

Frequently Asked Questions

Can I bring solid bar shampoo and soap instead of liquids?

Yes. Solid bar shampoo, conditioner, body soap, and solid lotion bars are completely solid and exempt from the 3-1-1 rule. Switching to solid toiletries is the single most effective way to eliminate liquid volume constraints.

Do I have to take my liquids bag out of my carry-on at modern airports?

At airport security lanes equipped with newer Analogic or Smiths Detection Computed Tomography (CT) 3D scanners, passengers are instructed to leave liquids and laptops inside their bags. However, older 2D X-ray checkpoints still require manual removal. Always check overhead lane signage.

Can I bring empty reusable water bottles through security?

Yes. Empty insulated flasks and water bottles of any size can pass through the security checkpoint without issue. Once through the screening area, you can fill your bottle at airport water refilling stations before boarding.