What’s Allowed in Carry-On Baggage on Southwest Airlines

Traveling can be an exciting adventure, but navigating airline baggage policies can sometimes feel like a daunting task. If you’re flying with Southwest Airlines, you’re in luck—this carrier is known for its customer-friendly approach, including a generous baggage policy that stands out among U.S. airlines. Whether you’re a frequent flyer or preparing for your first trip, knowing what’s allowed in your carry-on baggage can save you time, money, and stress at the airport. This guide will walk you through Southwest Airlines’ carry-on rules, offering clear, original insights to ensure your journey starts smoothly. By the end, you’ll have a solid grasp of what you can pack, what to avoid, and how to make the most of Southwest’s policies—all tailored for a hassle-free travel experience as of March 12, 2025.

Southwest Airlines Carry-On Basics: What You Can Bring

Southwest Airlines allows each passenger to bring one carry-on bag and one personal item aboard the plane at no additional cost. This is a standout feature, as many budget airlines charge extra for carry-ons. The carry-on bag must fit in the overhead bin and adhere to a maximum size of 10 x 16 x 24 inches (including handles and wheels). Your personal item—think a purse, laptop bag, or small backpack—should fit under the seat in front of you, with a suggested size limit of 18.5 x 8.5 x 13.5 inches. Unlike some airlines, Southwest doesn’t impose a strict weight limit for carry-ons, but you must be able to lift the bag into the overhead bin yourself. If you can’t, it’ll need to be checked.

This flexibility is a big win for travelers. You can pack a decent-sized suitcase as your carry-on and still bring a smaller bag for essentials like snacks, books, or electronics. Southwest’s no-fee policy for these items reflects its commitment to keeping travel affordable and straightforward. However, space in the cabin is finite, so arriving early to board can help secure overhead bin space, especially on busy flights.

Items That Don’t Count Toward Your Carry-On Allowance

Beyond the standard carry-on and personal item, Southwest permits several additional items that don’t count against your limit. These exceptions are designed to accommodate specific needs without penalizing passengers:

• Assistive Devices: Mobility aids like canes, crutches, walkers, or CPAP machines can be brought onboard for passengers with disabilities. There’s no limit to the number of assistive devices, making Southwest a practical choice for travelers with medical needs.
• Child Restraint Systems: If you’re traveling with a child who has a reserved seat, a car seat or booster can come onboard free of charge. This is a boon for families, ensuring safety without eating into your baggage allowance.
• Outer Garments: Jackets, hats, or other wearable clothing items don’t count as part of your carry-on or personal item. You can carry them separately or wear them to save space.
• Food for In-Flight Consumption: Snacks or meals in disposable packaging (like a sandwich in a ziplock bag) are allowed, perfect for avoiding pricey airport food.

These allowances showcase Southwest’s practical approach, prioritizing passenger comfort and necessity over rigid restrictions. For example, bringing a CPAP machine doesn’t force you to sacrifice your carry-on, a small but significant detail that sets Southwest apart.

Liquids, Gels, and Aerosols: The TSA 3-1-1 Rule

Southwest adheres to the Transportation Security Administration (TSA) guidelines for liquids, gels, and aerosols in carry-on baggage. This is the familiar 3-1-1 rule:

• 3.4 ounces (100 milliliters) or less per container.
• All containers must fit in one clear, quart-sized plastic bag.
• One bag per passenger, which you’ll need to remove and place in a screening bin at security.

This applies to items like toothpaste, shampoo, lotion, or hand sanitizer. For instance, a standard 3.4-ounce tube of toothpaste is fine, but a 6-ounce bottle of mouthwash won’t make the cut unless it’s in your checked bag. Exceptions exist for medications and baby-related liquids (like formula or breast milk), which can exceed 3.4 ounces if declared at security. Keep these in an accessible spot in your carry-on for inspection.

A pro tip: consolidate your liquids into travel-sized containers before you pack. This not only ensures compliance but also frees up space for other essentials. Southwest’s lack of carry-on fees means you can focus on packing smartly rather than worrying about extra costs.

Special Items Allowed in Carry-Ons

Southwest’s policy extends to several unique items that travelers might not expect to bring onboard:

• Alcoholic Beverages: You can carry small bottles (up to 3.4 ounces) in your quart-sized bag, as long as they’re under 70% alcohol by volume (140 proof). Anything stronger, like 151-proof rum, is banned entirely.
• Air Mattresses with Built-In Pumps: These are permitted with special instructions—ensure the pump’s battery complies with lithium battery rules (more on that later).
• Musical Instruments: Small instruments like a guitar or violin can count as your carry-on if they fit in the overhead bin or under the seat. Larger ones may need to be checked, but Southwest often accommodates them in the cabin if space allows.
• Medical Devices: Syringes, needles, or epinephrine auto-injectors (e.g., EpiPens) are allowed if properly secured and accompanied by a prescription or doctor’s note. Keep them in your carry-on for easy access.

These allowances reflect Southwest’s effort to balance safety with convenience. For instance, a musician traveling with a prized violin won’t face the stress of checking it, provided it fits the size limits.

Prohibited Items in Carry-On Baggage

While Southwest is lenient in many areas, certain items are strictly forbidden in carry-ons due to federal safety regulations. These align with TSA rules and apply across all airlines:

• Explosives and Flammable Items: Fireworks, gasoline, lighter fluid, and flares are no-gos. Even small sparklers are banned.
• Weapons: Firearms, ammunition, and sharp objects like knives or axes can’t come onboard. (Firearms and ammo can be checked in limited cases with proper declaration.)
• Compressed Gases: Aerosol insecticides or propane canisters are prohibited, though personal care aerosols like hairspray (under 3.4 ounces) are fine.
• High-Proof Alcohol: Anything over 70% alcohol by volume is out, as it’s considered flammable.
• Electronic Lighters: Arc, plasma, or electronic lighters are banned in both carry-on and checked bags due to their heat-generating potential.

Some items, like lithium batteries, have specific rules. Spare lithium batteries (e.g., for cameras or laptops) must be in your carry-on, not checked, with terminals protected to prevent short-circuiting. E-cigarettes are also carry-on only and can’t be used onboard.

If you’re unsure about an item, check Southwest’s website or the TSA’s “What Can I Bring?” tool before packing. Accidentally bringing a prohibited item can lead to delays or confiscation at security—better to plan ahead.

Pets and Carry-Ons

Traveling with a furry friend? Southwest allows small, vaccinated dogs and cats in the cabin, but their carrier counts as either your carry-on or personal item. The carrier must fit under the seat (max size: 18.5 x 8.5 x 13.5 inches) and costs an additional $95 fee each way. Only six pet carriers are allowed per flight, so book early. Pets aren’t permitted on international flights, and the carrier must be checked at the ticket counter, not the gate.

This policy is a mixed bag: it’s great for pet owners who want their companions close, but it does reduce your baggage options. Pack light if you’re bringing a pet, as you’ll lose either your carry-on or personal item slot.

Tips for a Smooth Carry-On Experience

To maximize Southwest’s carry-on policy, consider these practical strategies:

• Measure Twice, Pack Once: Use a tape measure to confirm your bag fits the 10 x 16 x 24-inch limit. A bag that’s too big will be gate-checked, potentially costing you $75 if you’ve already checked two bags.
• Layer Up: Wear bulkier items like a jacket or boots to free up space in your carry-on.
• Arrive Early: Southwest’s open seating means early boarding secures overhead bin space. Check in online 24 hours before your flight to snag a better boarding position.
• Keep Valuables Close: Electronics, medications, and important documents belong in your carry-on or personal item, not checked bags, for safety and accessibility.
• Use Packing Cubes: These can compress clothes and keep your bag organized, ensuring you stay within size limits.

Southwest’s two free checked bags (up to 50 pounds and 62 linear inches each) complement the carry-on policy. If your carry-on is too heavy to lift, check it instead—it’s free unless it’s your third bag.

Why Southwest’s Policy Stands Out

As of March 12, 2025, Southwest remains a rarity among U.S. carriers. While competitors like American or Delta charge for checked bags and sometimes carry-ons on basic fares, Southwest keeps it simple: no fees for your carry-on, personal item, or first two checked bags. This transparency eliminates the nickel-and-dime frustration many travelers face, making it easier to budget your trip. Plus, the lack of a carry-on weight limit (as long as you can lift it) adds flexibility other airlines don’t offer.

However, note that policies can evolve. Recent industry chatter suggests Southwest might tweak its “bags fly free” stance later in 2025, so stay updated via their official site. For now, though, it’s a traveler’s dream.

Final Thoughts

Southwest Airlines’ carry-on policy is a breath of fresh air in an industry often bogged down by fees and fine print. You can bring a carry-on, a personal item, and a range of special items—all without extra charges—while enjoying the freedom to pack essentials like snacks or medical devices. By understanding the size limits, TSA rules, and prohibited items, you can breeze through security and boarding with confidence. Whether you’re jetting off for a weekend or a cross-country haul, Southwest’s approach keeps your focus on the journey, not the baggage fees. Pack smart, board early, and enjoy the ride—Southwest has your back.