Southwest allows the largest carry-on of any major US airline, at 24 x 16 x 10 inches. It is two inches wider and one inch deeper than the 22 x 14 x 9 that Delta, American and United use.
That extra volume is real. A bag sold as an international cabin size will usually still clear Southwest, and Southwest bags routinely fail elsewhere.
The bigger news in Southwest baggage rules is what changed underneath that.
The Southwest baggage rules change nobody absorbed
Southwest built decades of marketing on two free checked bags. That policy ended in May 2025.
Most fares now pay standard per bag fees, the same as any other carrier. It is the single most important thing to know if you have not flown Southwest in a couple of years.
Free checked bags survive in a few cases only. Business Select fares qualify, as do A-List Preferred elites and Rapid Rewards Priority cardholders.
What bags cost now
| Bag | Fee |
|---|---|
| First checked bag | $45 |
| Second checked bag | $55 |
| Overweight, 51 to 70 lb | $100 plus the bag fee |
| Overweight, 71 to 100 lb | $200 plus the bag fee |
| Oversize, 63 to 80 linear in | $200 plus the bag fee |
Overweight and oversize charges stack on top of the standard fee. They do not replace it, so a heavy first bag is $145, not $100.
Standard checked bags run to 62 linear inches and 50 pounds.
The carry-on advantage still stands
Wheels, handles and attachments all count toward the measurement. Even so, it stays the most generous cabin allowance among the big four.
Southwest publishes no carry-on weight limit and does not vary the cabin allowance by fare. Whatever ticket you buy, the bag rules are identical.
That consistency is genuinely unusual. On most carriers the cheapest fare quietly removes something.
The personal item has no published dimensions and simply has to fit under the seat. Check your bag against the limit if you are near the line.
Do Southwest baggage rules still make it the value pick?
It depends entirely on whether you check a bag. For carry-on only travelers it stays excellent. The cabin allowance is the largest going.
For anyone checking two bags, the maths changed in 2025. Compare the total fare plus bags rather than the headline price.
Our baggage fees section covers how the carriers stack up once bags are added.
The bottom line
Southwest baggage rules now pair the best cabin allowance in US aviation with ordinary checked bag pricing. The famous free bags are gone for most passengers.
If you can travel with the 24 x 16 x 10 bag and nothing else, Southwest is still hard to beat. If you cannot, price it like any other airline.
Compare against the other carriers before booking. The standard cabin sizes show how much that extra two inches really buys.
Bag charges are where carriers diverge most. Our fees section lays out what each one asks for.
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