A display device includes pixels divided into blocks, a timing controller to generate image data based on input image data, a data driver to generate a data signal corresponding to the image data and supply the data signal to the pixels, and power supply to supply a power voltage to the pixels. In addition, the display device includes a power controller to calculate a first load value corresponding to the pixels, second load values corresponding to each of the blocks, and first peak grayscale values corresponding to each of the blocks based on the input image data. The power controller generates a power control signal to change a voltage level of the power voltage based on the first load value, the second load values, and the first peak grayscale values.