Units are very important for expressing any thermodynamic property; the same is true for specific heat. Energy in the form of heat is expressed in Joules (J) or kilojoules (kJ) which are the most common units associated with energy. One unit of mass is measured in grams or kilograms with regard to specific heat. Per one gram is the standard form used in tables of specific heat values, but references using one kilogram are sometimes seen. One degree of temperature is measured on either the Celsius or Kelvin scale, but usually Celsius. The most commonly associated units then for specific heat are J/(g•°C).