Douglas Flat (formerly, Douglasflat and Douglass Flat) is an unincorporated community in Calaveras County, California. It lies at an elevation of 1965 feet (599 m) and is located at . The community is in ZIP code 95229 and area code 209.
Douglas Flat was a roaring mining camp of the early 1850s. In 1857 the Harper and Lone Star Claims produced $130,000 worth of gold. The so-called Central Hill Channel, an ancient river deposit from which vast quantities of gold have been taken, is located here.
The town today is registered as California Historical Landmark #272.
The first post office opened in 1879, and was closed for a time in 1891 before reopening. The town's name honors Tom Douglas, an 1850s merchant.