The correlated color temperature (CCT) is widely used to describe the colors of display whites. The users can easily estimate the color of the display white based on CCT information. High CCT such as 7,000K means blush white and low CCT such as 4,000K means yellowsh white. However current CCT calculation method doesn't match with the visual appearance. Our study shows that CCT is highly correlated with warm-cool feeling of the white color, where warm-cool feeling is determined based on hue perception mainly. A series of hue perception experiments using the color stimuli near Planckian locus indicates that the orthogonal line from the Planckian locus in CIE u'v' chromaticity diagram can be used as the perceptionbased iso-CCT.