These rules were last checked on 10 Nov 2026, more than 100 days ago. Confirm on the airline's own page before you fly.
Southwest rules
An instrument within the carry-on limit of 24 × 16 × 10 in travels as a carry-on if space is available.
A larger instrument may still be carried on if it fits an overhead bin or under a seat and space is available.
Southwest recommends buying Priority Boarding or a fare with a boarding benefit to reach bin space first.
If it will not fit a bin, you can buy a non-refundable seat for it by contacting Southwest. It goes in a window seat with you beside it, not in an exit row.
Southwest says some instruments, such as cellos and double basses, cannot be secured in a seat and must be checked.
Checked instruments pay the standard bag fee. Oversize fees are waived; overweight fees apply from 51 to 165 lb. Maximum 150 linear inches and 165 lb.
In a soft case, a checked instrument travels under limited release and Southwest accepts no liability for damage.