# Travel >> Transportation >> Air Travel

Dimensions of the Space Under Airline Seats

Knowing the dimensions of the underseat space on an airline can help you pack properly for your travels. Although only one airline officially publishes its underseat dimensions, all airlines have a standard for carry-on baggage size that will fit in the allotted cabin space. In general, it's better to err on the side of safety and bring a smaller bag on board with you, so you can be sure it will fit under the seat comfortably.

Southwest Airlines
- Southwest Airlines is the only airline that officially publishes its underseat dimensions, specifically to help pet owners figure out if their carriers will fit easily inside the cabin. On a Southwest Boeing 737, the following dimensions are provided: window and aisle seats are 19 inches long by 14 inches wide by 8.25 inches high.
  
  Middle seats are the same dimensions, but are 19 inches wide.
Standard Carry-On Regulations
- Although other airlines don't publish their underseat dimensions, they do have fairly similar standards for carry-on baggage size. Air France, Delta Airlines, Northwest Airlines, United Airlines, US Airways and Virgin Atlantic all specify that a carry-on bag must not exceed 22 inches by 14 inches by 9 inches (or 45 inches total).
Other Carry-On Regulations
- Other airlines follow approximately the same carry-on size regulations, give or take a few inches. AirTran specifies a 55-inch carry-on; Alaska Airlines regulates 24 inches by 17 inches by 10 inches; American Airlines specifies 45 inches; America West and Continental are 51 inches; British Airways regulates 22 inches by 16 inches by 8 inches; and Spirit is 22 inches by 14 inches by 10 inches.