Southwest Airlines permits one personal item and one carry-on bag with maximum dimensions of 24 inches long, 16 inches wide, and 10 inches high. These limits apply to both domestic and international flights and ensure overhead bin compatibility.
The carry-on bag must fit within the specified size regardless of whether it's a hard-shell suitcase, soft-sided duffel, or rolling backpack. Bags exceeding these dimensions are subject to gate-checking at no charge, but passengers may face delays during boarding if they arrive late.
For reference, a standard 15-inch laptop fits comfortably inside a bag meeting these specs. A 20-liter backpack measuring 23 x 15 x 9 inches would qualify as compliant. Always measure your bag with a tape measure before arriving at the airport.
Southwest does not charge for carry-on bags. Passengers may bring one carry-on and one personal item (such as a purse, laptop bag, or small backpack) free of charge. Both items must fit under the seat or in the overhead bin.
At the gate, agents measure bags using a physical template. If a bag exceeds the 24 x 16 x 10 inch limit, it is checked at the gate. There is no fee for this, but it reduces access to luggage during the flight. Gate-checked bags are typically loaded last and retrieved first upon arrival.
In practice, many travelers exceed the size limit without realizing it. A 22-inch rolling suitcase with a 2-inch expansion zipper can reach 26 inches in length when stretched. This exceeds the limit and triggers a gate check.
Carry-ons for Southwest are commonly made from lightweight materials such as polycarbonate, nylon, or polyester. Hard-shell cases offer better protection for fragile electronics, while soft-sided bags allow flexibility in compression and fit into tight spaces.
Rolling bags with four wheels provide stability and ease of movement through terminals. Backpack-style carry-ons with shoulder straps are popular among travelers who want hands-free mobility. However, backpacks must still meet the size requirements and cannot have external attachments that increase bulk.
A traveler using a 20-inch duffel bag with a roll-top closure and reinforced corners reported that it passed inspection on five domestic flights. The bag measured 23.5 x 15.8 x 9.7 inches-just under the limit. The same bag, when packed with a bulky jacket and extra shoes, reached 25 inches in length due to internal stuffing.
Many assume that "carry-on" means any bag that fits in the overhead bin. But Southwest enforces strict size limits. A bag labeled "carry-on" by a manufacturer may still exceed 24 x 16 x 10 inches. Always verify actual dimensions, not just product labels.
Another misconception is that Southwest checks bags only if they're oversized. In reality, even a bag slightly over the limit-say, 24.5 inches long-is gate-checked. The airline uses a rigid template, not visual estimation.
Some travelers believe that bringing a larger bag in a smaller one (e.g., folding a duffel into a backpack) bypasses the rule. This doesn't work. The bag must pass inspection as-is. Southwest agents do not accept folded or compressed bags as valid carry-ons.
| Carrier | Max Carry-On Dimensions (inches) | Personal Item Size | Fee for Overweight Bag |
|---|---|---|---|
| Southwest Airlines | 24 x 16 x 10 | 18 x 14 x 8 (e.g., tote or laptop bag) | None (gate-checked free) |
| Alaska Airlines | 22 x 14 x 9 | 18 x 14 x 8 | None (gate-checked free) |
| Delta (Domestic) | 22 x 14 x 9 | 18 x 14 x 8 | None (gate-checked free) |
| Delta (International) | 22 x 14 x 9 | 18 x 14 x 8 | None (gate-checked free) |
Southwest's carry-on size is larger than Alaska Airlines' and Delta's domestic limits. Travelers switching between carriers must adjust their packing strategy accordingly. For example, a 22-inch roller bag that fits Alaska's limit may fail Southwest's.
When flying internationally, Delta enforces the same domestic carry-on size. However, international flights may require additional documentation for electronics or liquids. Always confirm policies at the time of booking.
I flew from Houston to Las Vegas with a 24 x 16 x 10 inch hard-shell suitcase. I packed:
The bag fit under the seat and in the overhead bin. I did not need to gate-check. The weight was 18 pounds-well under Southwest's 50-pound limit for carry-ons.
On return, I added a gift-wrapped sweater. The bag expanded slightly when closed. I measured it at 24.2 x 15.9 x 10.1 inches. At the gate, the agent flagged it. I was asked to gate-check it. No fee applied, but I lost access to my bag during the flight.
This shows that even minor expansions can trigger a gate check. Always measure after packing.
Always measure your carry-on bag with a tape measure before arriving at the airport. Use a ruler or a printed template to test fit. Many airports sell carry-on size checkers at security checkpoints.
Southwest's carry-on size is generous compared to other U.S. airlines. But compliance requires attention to detail. A bag that fits in the overhead bin on one airline may not on another.
Staying within the size of carry on bag for Southwest Airlines prevents delays, avoids gate checks, and keeps your belongings accessible throughout the flight.