Ontario International Airport, ONT, has two terminals and a separate adjacent facility for international arrivals. The terminal numbering scheme was designed to adapt future growth under a prior airport master project.
Terminal 2 occupies 265,000 square feet (24,600 m2) and consists of 12 gates (Gates: 201–212). Terminal 4 covers 265,000 square feet (24,600 m2) and includes 14 gates (Gates: 401–414). Concerning the International arrivals facility, it has only two gates for only arrivals, and the building also houses a U.S. Customs and Border Protection and Federal Inspection Service (FIS). However, International charter routes depart from the main terminals. At the terminals, there is a circulator bus that runs around the airport and offers connections between terminals, rental car, remote parking garages, and public transit stops.