According to the United States Census Bureau, the CDP has a total area of , all of it land.
Concord is mostly bounded by highways-by Interstate 255, U.S. Route 67 (locally called Lindbergh Boulevard and co-signed here with U.S. Route 50 and U.S. Route 61), Route 21 (known locally as Tesson Ferry Road), and Route 30 (known locally as Gravois Road).