An optical compensation method for a display device including a pixel is provided. The method includes: providing test data having a first grayscale value to the display device; measuring a luminance of the pixel which emits light based on the test data; and calculating a compensation grayscale value based on a second target luminance and the measured luminance of the pixel. The second target luminance is lower than a first target luminance which is set based on the first grayscale value.