Southwest Airlines’ carry-on bag sizer feature first drew attention in 2018 as a way for travelers to check their luggage size before arriving at the airport. The tool used a phone camera to scan a bag and help passengers see whether it would likely fit in the overhead bin.
The feature, which does not appear to be currently promoted on Southwest’s app pages or baggage support pages, gave travelers a way to check their luggage before leaving home, especially as airline baggage rules and fees continue to change. A recent check of the app also did not show the tool in the main menu.
How Southwest’s Carry-On Bag Sizer Works
After opening the app, users could access the bag sizer, follow the tutorial, scan the floor with their phone, and place the suitcase on the ground with the handle pushed down. The app then used the phone camera to estimate whether the bag would fit in the overhead bin.
The feature arrived during a period when more travel companies were experimenting with augmented reality tools for baggage. KAYAK introduced a similar bag measurement tool in September 2018, allowing users to scan a suitcase with a phone camera and compare the result with airline baggage policies before going to the airport.
What Southwest Travelers Should Know About Bag Rules Now
Reuters reported that Southwest ended its long-standing free checked-bag policy in 2025 and began charging many passengers for checked luggage. The policy change includes exemptions for some elite customers, premium fare passengers, Southwest credit card holders, and active-duty military customers.
Southwest’s current travel fee page says all ticketed passengers may still bring one carry-on bag and one personal item for free. The airline lists the carry-on limit as 24 inches by 16 inches by 10 inches. Checked-bag fees now apply to Basic, Choice, and Choice Preferred fares, while Choice Extra fares and Rapid Rewards A-List Preferred members receive two free checked bags. A-List members and Rapid Rewards credit card members receive one free checked bag.
Southwest’s fee chart lists standard checked-bag charges that vary by booking date and itinerary, including $45 for the first checked bag and $55 for the second checked bag for U.S. mainland travel booked or changed on or after April 9, 2026. For passengers flying Southwest today, the safest approach is to measure the suitcase at home, including wheels and handles, confirm the airline’s current policy before departure, and allow airport staff to make the final baggage decision at check-in or boarding.
