A display device includes a degradation compensator, a controller, a data driver, and a display panel. The degradation compensator generates a first fitting function and a second fitting function based on image data, generates a compensation function through a harmonic mean of the first and second fitting functions, and generates a compensation value based on the compensation function. The controller receives the compensation value, and generates input image data to which the compensation value is applied. The data driver receives the input image data to which the compensation value is applied, and converts the input image data into a data voltage. The display panel includes pixels, in which each of the pixels includes a pixel circuit which receives the data voltage and a light-emitting element electrically connected to the pixel circuit.