The Watt-hour per kilogram is the reference unit used to measure or indicate the density of energy contained or storable in a body. Its abbreviated form is .
The Watt-hours per kilogram express the as a function of the mass of the body: it is then called mass .
In the same way, it is possible to formulate the according to the volume of the body taken into account: in this case, the is said to be volumetric. The unit used here is the Watt-hour per cubic meter, abbreviated as Wh/m3.
The Watt-hour per kilogram () comes in several variants depending on the magnitude of the taken into account:
The mass is an important data in energy production and .
The unit Watt-hour per kilogram is widely used in the transportation industry to evaluate the energy contained in a fuel or that can be stored in a battery.
The mass is very variable depending on the material.
Thus, the mass is rather expressed in for:
The kWh/kg is used more for:
At the nuclear scale, it is more appropriate to use /kg, with for example: