What are the TSA carry-on liquid rules?

The TSA 3-1-1 rule: liquids in containers of 3.4 oz (100ml) or less, all fitting in 1 quart-sized clear zip bag, 1 bag per passenger. Remove the bag and place it in the tray at screening.

Does TSA PreCheck let you keep your shoes on?

Yes. TSA PreCheck passengers keep shoes on, laptops in bags, liquids in bags, belts on, and light jackets on. It significantly reduces screening time at participating airports.

What is the standard carry-on size for US airlines?

Most major US airlines allow 22 × 14 × 9 inches for carry-on bags. Southwest is more generous at 24 × 16 × 10 inches. These dimensions include wheels and handles.

Do US airlines have a carry-on weight limit?

No. American Airlines, Delta, United, and Southwest do not publish a carry-on weight limit for domestic flights. You may bring as heavy a bag as you can safely lift into the overhead bin.

What is CLEAR and how is it different from TSA PreCheck?

CLEAR uses biometric identity verification (fingerprint or iris scan) to skip the ID check line. CLEAR does not bypass the physical screening — you still go through the scanner. PreCheck skips the physical screening steps. Some travelers use both.

Can I bring food through TSA security?

Yes. Solid food is permitted in carry-on bags. Liquid or gel foods (peanut butter, yogurt, dips) are subject to the 3-1-1 rule. Frozen items are allowed if fully frozen when screened; partially thawed items may be rejected.

US Airport Carry-On Rules: TSA, PreCheck & Airline Limits

Flying in the United States means navigating two separate systems: TSA security screening rules and individual airline carry-on policies. US security rules are administered by the Transportation Security Administration (TSA) and apply at virtually every commercial airport in the country. Understanding both layers helps you pack correctly, choose the right security lane, and avoid fees at the gate.

TSA Security: Standard Lane Rules

The 3-1-1 Liquid Rule

The TSA applies the 3-1-1 rule to liquids in carry-on bags:

3.4 oz (100ml) or less per container
1 quart-sized clear zip-top bag
1 bag per passenger

Remove the liquids bag from your carry-on and place it in the bin before the X-ray scanner. Gels, creams, pastes, and aerosols all fall under this rule. Exempt from 3-1-1: medications (including liquid medication in any quantity, with a label), baby formula and breast milk, and juice for infants.

What to Remove in Standard Lanes

In standard TSA lanes without PreCheck:

Shoes off — all footwear must be removed and placed in a bin
Laptop out — must be removed from the bag and placed flat in a bin
Liquids bag out — the 1-quart zip bag goes in a separate bin
Belt and heavy jacket off — metal items and thick outerwear

This process takes time. Budget extra minutes at large airports, especially JFK, LAX, O'Hare, and Hartsfield-Jackson Atlanta, where queues can be long during peak hours.

TSA PreCheck: What You Get

TSA PreCheck is a paid program (approximately $85 for 5 years) that grants access to dedicated security lanes at over 200 US airports. In PreCheck lanes:

Shoes stay on
Laptop stays in the bag
Liquids stay in the bag
Belt stays on
Light jacket stays on

PreCheck does not guarantee a shorter queue, but the reduced steps make throughput faster in PreCheck lanes than in standard lanes, even when volume is comparable. PreCheck is worth it for anyone who flies more than two or three times a year domestically.

Enrolling in TSA PreCheck

Apply online at the TSA website, complete an in-person appointment at an enrollment center (located at most major airports and many shipping stores), and provide fingerprints. Approval typically arrives within 3–5 days. Your Known Traveler Number (KTN) goes into your airline profile and appears on boarding passes.

CLEAR: Identity Verification, Not Screening Bypass

CLEAR is a private biometric identity program available at over 50 major US airports. CLEAR uses fingerprint or iris scans to verify your identity at the identity verification step — the document check before the physical screening.

Key distinctions:

CLEAR skips the ID line only — you still go through full TSA physical screening (shoes off, laptop out in standard lanes)
CLEAR + PreCheck is the fastest combination: CLEAR bypasses the document queue, PreCheck bypasses the physical screening steps
Cost is approximately $189/year; Delta SkyMiles and United MileagePlus members receive discounts

Airport-Specific Tips

JFK (New York)

JFK has multiple terminals operated by different airlines with separate security checkpoints. Terminal 4 handles Delta international, Emirates, and several others. Terminal 8 is American Airlines. PreCheck is available at all JFK terminals but queue lengths vary significantly by terminal and time of day.

LAX (Los Angeles)

LAX is undergoing significant terminal renovations through 2026. Security queues at LAX can be long during morning departures (6–9am) and evening returns (4–8pm). The automated screening lanes at Terminals 4 and 5 are faster — look for signage directing you to AUTOMATED lanes.

ATL (Hartsfield-Jackson Atlanta)

ATL is the world's busiest airport. Delta operates from Concourses A through F and the Maynard H. Jackson International Terminal. Security at the main checkpoint (before the underground train) is the primary bottleneck — the PreCheck lanes here move substantially faster than standard lanes during peak travel periods.

O'Hare (Chicago)

O'Hare Terminal 1 serves United; Terminals 2 and 3 serve American and other carriers. PreCheck lanes are available in all terminals. Security at Terminal 3 during morning peaks (6–9am) can be particularly congested.

US Airline Carry-On Size Limits

US domestic carriers have no published weight limit on carry-on bags. Size limits are published but enforcement is inconsistent — most US carriers rely on the overhead bin fitting requirement rather than measuring bags at the gate.

Airline	Max Carry-On Size	Weight Limit	Personal Item
American Airlines	22 × 14 × 9 in (56 × 36 × 23 cm)	None	Under-seat bag
Delta Air Lines	22 × 14 × 9 in (56 × 36 × 23 cm)	None	Under-seat bag
United Airlines	22 × 14 × 9 in (56 × 36 × 23 cm)	None	Under-seat bag
Southwest Airlines	24 × 16 × 10 in (61 × 41 × 25 cm)	None	Under-seat bag

Southwest's dimensions are meaningfully more generous than the three legacy carriers. Southwest also includes 2 checked bags free, which changes the packing calculus for many travelers.

Basic Economy and Carry-On Exclusions

All three legacy carriers offer Basic Economy fares that exclude overhead bin carry-on access:

American Airlines Basic Economy: personal item under seat only; carry-on charged at the gate
Delta Basic Economy: personal item under seat only on most domestic routes
United Basic Economy: personal item under seat only; carry-on charged at the gate at a premium rate

Southwest does not have Basic Economy restrictions — all fares include 2 checked bags and carry-on.

Prohibited Items in US Carry-On Bags

Common items not allowed in carry-on:

Firearms (may be checked in declared locked containers)
Knives with blades over 4 inches
Flammable liquids and gases
Self-defense sprays (pepper spray) over 4 oz
Spare lithium batteries over 100 Wh must be in carry-on (not checked)

The TSA prohibited items list is available at tsa.gov and is searchable by item.

Practical Tips for US Airport Security

Sign up for PreCheck before your first trip. The time savings on domestic flights are consistent and the enrollment process is straightforward. Expedited enrollment at many major airports takes under 10 minutes.

Pack a separate quart bag for liquids and put it on top. The most common security delay is passengers unpacking bags at the tray to find their liquids. A dedicated pouch in the outer pocket eliminates this.

At LAX, ATL, and JFK, arrive at least 2.5 hours before domestic departure during summer. Security queue times at these airports during peak periods can exceed 45 minutes in standard lanes.

Southwest's larger size limit matters. If you're flying Southwest with a wheeled carry-on that doesn't fit the 22 × 14 × 9 inch limit, Southwest's 24 × 16 × 10 inch limit may save you a gate check fee.