I just measured the actual pixel (lit) portion of the screen -- it's about 24 1/2 X 13 1/2 minus about 1/16 in each dimension. The diagonal length is about 28", which of course can also be derived using that equation made famous by Pythagoras. That's 3480 X 2160 pixels, where the "4K" comes from the approximate pixels along the horizontal. Hope that helps.