A display device includes: a pixel part partitioned into blocks; a scale factor provider which calculates a first load value of input image data for the pixel part, calculates a second load value of the input image data for each block, and generates a scale factor based on the first and second load values; and a timing controller which generates image data by scaling gray values of the input image data based on the scale factor. The scale factor provider generates a first scale factor for commonly controlling the gray values for the blocks based on the first load value, when the first load value is greater than or equal to a reference load value, and generates a second scale factor for controlling gray value for each block based on the first and second load values, when the first load value is less than the reference load value.