Classically and Newtonianly, it's the sum of the chemical energy if any,
the electrical energy if any, the thermal energy if any, and the mechanical
energy consisting of potential and kinetic energy if any.
The mechanical energy, consisting of potential and kinetic energy if any, is
0.001 x [ (acceleration of gravity x height) + (1/2) (speed)² ] .
But I've got a sneaky hunch that you're not talking about any of these.
You want to know how much [ mc² ] there is in 1 gram of mass. No prob.
E = m c² = (0.001) x (3 x 10⁸)² = 9 x 10¹³ joules
That's the energy that a 1,000-watt toaster uses
in 2,852 years of continuous toasting.