Southwest Carry-On Size 2025: Rules, Limits & Packing Tips

Your personal item should hold the essentials you’ll need during the flight, such as medications, travel documents, electronics, or a good book. It must slide under the seat without blocking your legroom. If the airline staff thinks it’s too big, they may ask you to stow it elsewhere.

To avoid surprises, test fit your personal item under a normal chair (or similar) at home. If it slides under without bulging, you're good to go.

Why Doesn’t Southwest List a Weight Limit?

Unlike some airlines, Southwest does not publish a strict weight limit for carry-ons and personal items. Their rule depends on your ability to lift and stow the bag in the overhead bin. If you struggle lifting it, agents may ask you to gate-check it.

So pack smart and balanced:

• Spread heavy items evenly; don’t put all the weight on one side. 

• Use soft packing cubes or flexible containers.

• Avoid overstuffing; leave a little room so you can adjust the shape.

Also read How to Change Flight on Southwest

What’s Changed in 2025 About Checked Bags?

In 2025, Southwest updated fare types and what’s included in each ticket. Now, some fares that once included free checked bags require you to pay. The carry-on rules remain unchanged, but you need to pay attention to checked baggage when you book.

Here’s the shift:

• Basic, Choice, and Choice Preferred fares may charge for checked bags unless you pick a fare that includes them.

• Prices for checked bags vary; many travelers pay around $35 for the first bag, $45 for the second, one way.

• Some fare tiers or loyalty levels still include one or two free checked bags as a benefit.

Before you fly, always check your fare’s baggage allowance. Even if the carry-on stays the same, checked bag plans now play a bigger role in your total cost.

Also read Southwest Red Eye Flights 

How Do Pets, Strollers, and Special Items Work on Southwest Flights?

If you’re flying with a furry friend or extra items like strollers and musical instruments, Southwest has clear rules to help you plan easily.

For pets, Southwest allows small cats and dogs in the cabin for a one-way pet fee (around $95 each way). The pet carrier must fit under the seat in front of you and counts as either your personal item or your carry-on. The maximum carrier size is typically 18.5 x 13.5 x 9.5 inches. Make sure your pet is comfortable, with absorbent pads and some ventilation holes for airflow.

If you’re travelling with a stroller or car seat, you can check them for free either at the ticket counter or gate. Southwest makes this simple for families; you just tag them before boarding.

Musical instruments can be carried onboard if they fit in the overhead bin or under the seat. Otherwise, you may purchase a separate seat for them. Soft cases are better for fitting within the 24 x 16 x 10-inch allowance.

Pets, kids’ gear, and instruments are welcome on Southwest, but they follow the same rule: they must fit safely or be checked in advance.

What Happens on Full Flights When Bin Space Fills Up?

Southwest flights are often busy, especially on popular routes or weekends. When overhead bins fill up, boarding order becomes your best friend. Passengers who board earlier usually find bin space near their seats, while later groups may need to store bags further down the aisle or check them at the gate.

Gate-checking a bag is usually free; it will be tagged and sent directly to your final destination. Still, it’s smart to keep essentials (passport, wallet, chargers, medication) in your personal item in case your carry-on gets checked.

Here are a few smart tips for full flights:

• Remove anything you’ll need during the flight before boarding.

• Place your bag wheels-first into the overhead bin; it saves space for others.

• Use smaller under-seat bags to leave room for other passengers.

Being organised not only helps you find space but also speeds up boarding for everyone.

What Is the Best Strategy for Packing Within the Rules?

You don’t need to buy expensive gear to follow the rules. A simple and well-planned strategy can make your carry-on fit perfectly.
Here’s how:

• Measure first: Always check your suitcase dimensions before leaving home.

• Use packing cubes: They compress clothes and help you organise easily.

• Wear bulky items: Jackets, boots, or hoodies take up space; wear them instead.

• Limit liquids: Keep them in TSA-approved 3.4 oz containers inside one clear zip bag.

• Keep essentials close: Wallet, medications, and ID should always go in your personal item category.

A well-organised bag not only fits the 24 x 16 x 10-inch limit but also makes unpacking quick when you arrive.

Why Book with Flightsquest for Your Next Southwest Trip?

Travelling light on Southwest Airlines has never been easier when you understand the new 2025 policies. The airline’s carry-on size limit, 24 x 16 x 10 inches, remains your best travel ally. Stick to one carry-on and one personal item, and you’ll save on baggage fees, boarding time, and unnecessary delays.

If you’re planning your next trip, choose Flightsquest to book your Southwest tickets. You’ll get transparent prices, smooth flight comparisons, and easy online booking with no hidden surprises. Whether it’s a business trip or a family getaway, Flightsquest helps you travel smart, light, and within budget.

So, pack your essentials, measure your bag, and book your next flight confidently with Flightsquest today.

FAQs

1. Can I bring a duty-free shopping bag in addition to my carry-on and personal item?

Yes, duty-free bags are usually allowed in addition to your two items, as long as they fit safely in overhead bins or under your seat.

2. Does Southwest measure carry-on bags at the gate every time?

Not always. If your bag looks within limits and fits in the sizer, you can board smoothly. Oversized bags may be tagged for gate check.

3. Can I carry food or snacks in my personal item?

Absolutely. Southwest allows packaged food and dry snacks in both carry-on and personal bags. Just follow TSA’s liquid rules for drinks or sauces.

4. What happens if my carry-on doesn’t fit in the overhead bin?

If bins are full or your bag exceeds size limits, the gate agent will check it for you, usually free of charge, to your final destination.

5. Are there any exceptions for medical devices or equipment?

Yes, medical devices like CPAP machines do not count toward your carry-on limit. They must, however, fit safely under the seat or in the overhead bin.