Kirby is an unincorporated census-designated place located in the U.S. state of Arkansas. It is within Pike County on U.S. Route 70 in halfway between Daisy and Glenwood. It has a total area of 14.46 square miles at 34°15′01″N 93°38′29″W. The elevation is 663 feet above sea level. As of the 2010 census data, it had a total population of 447. Estimated per capita income in 2015 was $19,963.