Bigger than many of us realize. On many maps, Africa looks to be about the size of Greenland due to the distortion of making a round object appear flat. Not surprisingly, people who grow up with these distorted maps seriously miscalculate the size of different countries and continents. Geographic illiteracy, if you will.
This infographic by Kai Krause, which I stumbled across on Information is Beautiful, visually explains the true size of Africait's roughly the size of China, India, Japan, the U.S. and Europe combined.