Flying these days often involves a more relaxed dress code than in the past. However, several airlines maintain specific guidelines regarding passenger attire to ensure comfort and safety for everyone on board. Let's explore the dress codes of various airlines, from casual to smart casual.

Spirit Airlines recently formalized its dress code, prohibiting passengers from boarding if they are barefoot, inadequately clothed (including see-through items or exposed private areas), or wearing clothing deemed lewd, obscene, or offensive.

Hawaiian Airlines

Hawaiian Airlines requests passengers refrain from wearing bathing suits, requiring attire that covers the upper torso. While shorts are acceptable, speedos and bikini bottoms are not permitted. Shoes are also mandatory.

Hawaiian Airlines customers have to leave their bathing suits for the beach.  (iStock)

Southwest and United Airlines

Both Southwest and United Airlines share similar guidelines, prohibiting lewd, obscene, or patently offensive clothing. Shoes are required for all passengers.

Customers can't wear "lewd" clothing on board Southwest flights. (Angus Mordant/Bloomberg via Getty Images)

American Airlines

American Airlines encourages passengers to "dress appropriately," prohibiting bare feet and offensive clothing.

American Airlines bans "offensive clothing" on its planes. (Drew Angerer/Getty Images)

Delta Air Lines

Delta Air Lines addresses passenger attire more broadly, stating that individuals whose conduct, attire, hygiene, or odor creates an unreasonable risk of offense or annoyance to other passengers may be removed from the flight.

Qatar Airways

Qatar Airways implements a "smart casual" dress code for business class and above, prohibiting shorts, sportswear, and overly revealing clothing. The airline emphasizes the importance of respecting fellow passengers through appropriate attire.

Qatar Airway's passengers in business class must wear "smart casual" clothes. (Richard Baker/In Pictures via Getty Images)

Certain airlines have dress codes for their customers.  (iStock; Getty Images)