A display device includes pixels which displays an image based on image data, a driving voltage generator which provides a driving voltage to each of the pixels, and a driving voltage controller which calculates block pixel numbers corresponding to first to nth grayscale blocks based on the image data, calculates maximum grayscales with respect to the first to nth grayscale blocks based on the image data, determines a maximum grayscale block among the first to nth grayscale blocks by comparing the block pixel numbers to minimum pixel numbers corresponding to the first to nth grayscale blocks, determines a maximum grayscale with respect to the maximum grayscale block based on the maximum grayscales, calculates a load of the image data, calculates a voltage drop amount of the driving voltage based on the load, and calculates a magnitude of the driving voltage based on the maximum grayscale and the voltage drop amount.