An integrally bladed rotor comprises a hub centered about an axis and having a plurality of blades extending radially outwardly of the axis across a span. Each of the blades includes an airfoil extending between a leading edge and a trailing edge, and having a pressure side and a suction side. The airfoil has a thicker portion at the trailing edge, and at a radially inner portion of the span, and over a limited percentage of the span, such that the thicker portion does not extend beyond 50 percent of the span. An axial distance is defined between the trailing edge and the leading edge. The thicker portion extends for less than 50 percent of the axial distance, and is on the pressure side. A gas turbine engine is also disclosed.