Southwest permits one carry-on bag up to 24 × 16 × 10 inches and one personal item for a ticketed passenger. Count the wheels, handles, and anything attached to the carry-on. Your smaller item goes under the seat; Southwest’s page doesn’t give one universal inch-by-inch box for it.
Which item is which?
| Item | Published rule | Typical placement |
|---|---|---|
| Carryon bag | Up to 24 × 16 × 10 in outside | Overhead bin |
| Personal item | Must fit under the seat | Underseat space |
A roller, tote or small suitcase can be a carryon if its full exterior fits. A purse, laptop case or backpack may be the personal item if it fits beneath the seat. A pet carrier can count as one of those two items, so a traveler with a pet should not assume a third ordinary bag.
A measurement example
Say your suitcase measures 24 × 15.5 × 9.5 inches before you fill the outside pocket. If that pocket pushes the width to 16.5 inches, the bag is over Southwest’s 16-inch side limit. Close the bag and measure at its widest point. The carry-on size checker compares the three sides, but it can’t reserve overhead space on your flight.
Southwest advises travelers with an oversized carryon or more than the allowed cabin items to check the bag at the ticket counter before reaching the gate. If it is checked, remove spare batteries and power banks and keep valuables with you. The airline's baggage fee table is a separate checked-bag question; a permitted cabin bag is not a free third checked piece.
If your itinerary includes a partner airline, its cabin and personal-item limits can differ. Check each operating segment. For the date-specific checked-bag policy, see Southwest baggage fees.
Airline sources
Sources last checked 2026-10-31. Match the fare and flight in your booking before you pay or pack.