You may use this calculator to convert from mass units (kilograms [kg], pounds [lb], pound moles [lbmol], or moles [gmol]) to energy units (British Thermal Units [Btus] or Million Joules [MJ]).
The lower heating value (also known as net calorific value) of a fuel is defined as the amount of heat released by combusting a specified quantity (initially at 25°C) and returning the temperature of the combustion products to 150°C, which assumes the latent heat of vaporization of water in the reaction products is not recovered. The higher heating value (also known gross calorific value or gross energy) of a fuel is defined as the amount of heat released by a specified quantity (initially at 25°C) once it is combusted and the products have returned to a temperature of 25°C, which takes into account the latent heat of vaporization of water in the combustion products.
The abbreviation, scf, stands for standard cubic feet. For gaseous and liquid fuels, the heating values, in units of Btu/lb, are calculated based on the values in Btu/scf or Btu/gal and the corresponding fuel density values. See Lower and Higher Heating Values of Hydrogen and Fuels. The heating values in units of MJ/kg are converted from the heating values in Btu/lb.