Kailua is a census-designated place (CDP) in Hawaiʻi County, Hawaii, United States, in the North Kona District of the Island of Hawaiʻi. The population was 11,975 at the 2010 census. It is the center of commerce and of the tourist industry on West Hawaiʻi. Its post office is designated Kailua-Kona to differentiate it from the larger Kailua located on windward Oʻahu, and it is sometimes referred to as Kona in everyday speech. The city is served by Kona International Airport, located just to the north in the adjacent Kalaoa CDP. Kailua-Kona was the closest major settlement to the epicenter of the 2006 Hawaiʻi Earthquake.
Kailua is located at 19°39′0″N 155°59′39″W (19.649973, −155.994028), along the shoreline of Kailua Bay and up the southern slope of Hualālai volcano. There are no major rivers or streams in Kailua or on the Kona side of Hawaii.
According to the United States Census Bureau, the CDP has a total area of 39.8 square miles (103 km2), of which, 35.5 square miles (92 km2) of it is land and 4.3 square miles (11 km2) of it is water. The total area is 10.71% water.
The Kailua-Kona postal code is 96745. Other communities located in this zip code include: Kalaoa, Kealakehe, Kahaluʻu, and Keauhou.