To provide a float glass for a display substrate, of which the high temperature viscosity is low, without impairing properties for a substrate glass for a display.A float glass for a display substrate, characterized in that its composition consists essentially of, as represented by mass % based on oxide, from 52 to 62% of SiO2, from 5 to 15% of Al2O3, from more than 0% to 9% of MgO, from 3 to 12% of CaO, from 9 to 18% of SrO, from 0 to 13% of BaO, from 25 to 30% of MgO+CaO+SrO+BaO, from 6 to 14% of Na2O+K2O+Li2O, from 0 to 6% of ZrO2 and from 0 to 1% of SO3, the temperature of glass melt corresponding to the viscosity of 102 dPa·s is at most 1,520° C., the temperature of glass melt corresponding to the viscosity of 104 dPa·s is at most 1,120° C., the glass transition temperature is at least 610° C., and the specific gravity is at most 2.9.