Calculate Energy

There are several types of energy that can be converted into each other. Three of the most common, energy in electrical current, in mechanical work and kinetic energy can be calculated here. The SI unit of energy is the joule (J), which is equal to one watt second (Ws) and one newton meter (NM). The kilowatt hour (kWh), which corresponds to 3.6 million joules, is common for electricity metering.

Electric Current

Please select the units first. From two values of voltage, current and electrical power, the third can be calculated. Likewise, the third can be calculated from two values of electrical power, time and electrical energy.

Electric power:
Electric energy:

Example: An average lightning bolt has a current of 10 kiloamperes at a voltage of 10 megavolts. This corresponds to 100 billion watts (100 GW). With a duration of 36 microseconds, exactly one kilowatt hour of energy is then released.

Mechanical Work

Here a certain force acts over a certain distance. Please select the units first. The third value can be calculated from two values of force, distance and work.


Example: in order to lift a weight of ten kilograms (≙ 98.1 newtons, see converting kilograms and newtons) five meters up, you have to use energy of almost half a kilojoule.

Kinetic energy

The kinetic energy is what it takes to achieve a movement. Please select the units first. The third value can be calculated from two values of mass, speed and energy. The formula is Ekin = m * v² / 2; 1 J = 1 kg * m² / s²

Mass m:
Velocity v:
Kinetic energy:

Example: a 900 kg car driving 120 km/h has a kinetic energy of 500 kilojoules.

Physics commonly uses SI units. Here is a calculator to convert units.