At standard temperature and pressure, the density of NaOH, or sodium hydroxide, is 2.13 grams per cubic centimeter. The STP standard assumes a temperature of 32 degrees Fahrenheit and 0.987 standard atmosphere.
As with all substances, the density is determined by dividing the mass by its volume. The value of both those measurements is dependent on the temperature and the pressure exerted on the substance. Generally, the density of a substance decreases as temperature increases and increases as the temperature decreases. The reverse is true with pressure, as the density increases with increasing pressure and decreases as the pressure decreases.