An expedition to the area in the 1990s claimed that nearby Monte Pissis was even higher than Ojos del Salado. Later measurements using more precise equipment showed that Ojos del Salado is about higher than Pissis; furthermore, a 2007 Chilean–Argentine–European expedition organized by Andes Magazine and Azimut 360, using even more accurate instruments and performing surveys on both Ojos del Salado and Monte Pissis, found the former to be and the latter Although this fits within recent handheld GPS surveys which have estimated the mountain to be between and , the vertical error margin of the expedition's equipment , leaves the mountain's precise altitude uncertain.