This is a table of density (kg/L) and the corresponding concentration (% weight) of sodium hydroxide in water at a temperature of 20 degrees centigrade. The table was taken from the chemical engineering handbook. The calculator does automatic interpolation calculation for density or concentration values that are between those in the table. In effect, any value within the range of the table can be calculated. Just input the density of the solution and the calculator will compute for the corresponding concentration. Or input the concentration to get the corresponding density. Please input only one value and leave the value to be calculated blank. In practice, density is determined by means of a hydrometer or by weighing a known volume of a solution. This calculator can be used in conjunction with the other three sodium hydroxide calculators in this set.