Fairborn is a city in Greene County, Ohio, United States. The population was 34,620 at the 2020 census. It is a suburb of Dayton and part of the Dayton metropolitan area. The city is home to Wright State University, which serves nearly 12,000 undergraduate and graduate students. The city also hosts the disaster training facility known informally as Calamityville. It is the only city in the world named Fairborn, a portmanteau created from the names Fairfield and Osborn.