A display device includes a pixel unit including pixels, a timing controller configured to generate image data based on input image data, a data driver configured to generate a data signal corresponding to the image data and supply the data signal to the pixels, a power supply configured to supply a power voltage to the pixel unit, and a power controller configured to calculate a load value and a peak grayscale value based on the input image data, and to generate a power control signal to change a voltage level of the power voltage based on the load value and the peak grayscale value.