|Founded||February 5, 1777|
|Named for||William Pitt, 1st Earl of Chatham|
|• Total||632 sq mi (1,640 km2)|
|• Land||426 sq mi (1,100 km2)|
|• Water||206 sq mi (530 km2) 32.6%|
|• Density||470/sq mi (180/km2)|
|Time zone||UTC−5 (Eastern)|
|• Summer (DST)||UTC−4 (EDT)|
Chatham County is a county in the U.S. state of Georgia, and is on the state's Atlantic coast. The county seat and largest city is Savannah. The county was created on February 5, 1777, and is named after William Pitt, 1st Earl of Chatham.
At the 2020 census, 295,291 people lived in Chatham County. This makes it the sixth-most populous county in Georgia, and the most-populous Georgia county outside the Atlanta metropolitan area. It is part of the Savannah metropolitan area.