A display device includes a display panel including a plurality of pixels, and a panel driver configured to drive the display panel. The panel driver receives input image data at a variable input frame frequency, stores the variable input frame frequency as a previous frame frequency by monitoring the variable input frame frequency, determines a reference frequency based on the previous frame frequency, determines a reference luminance as a luminance of the display panel at the reference frequency, and adjusts data voltages applied to the plurality of pixels such that a luminance of the display panel at the variable input frame frequency becomes the reference luminance.