Calculator for Power and Energy

Calculates power, energy or duration from the other two values. Power is physical energy, which is transferred in a certain amount of time. It is calculated as energy per time. Energy is physical power, which is performed over a certain timespan. It is calculated as power times time.

Energy E:
Time t:	d h m s
Power P:

Round to decimal places.

Please enter two values and select the units, the third value will be calculated. The formula for power is P = E / t, for energy it is E = P * t. The unit of power, watt, is calculated as joules per second, 1 W = 1 J / s. Time is counted as days (d), hours (h), minutes (m) and seconds (s).

Example: if a solar plant produces 3 kilowatt hours of electricity within 90 minutes, it has an average power of 2000 watts.

Watt is the unit of power, named after the Scottish scientist and engineer James Watt. It is in use since 1889, has been part of the SI system of units since 1960 and is therefore the scientific standard worldwide. One watt corresponds exactly to one ampere-volt, the previously common unit. So W=AV applies, this is also called electrical watt. Likewise, one watt corresponds to one joule per second, W=J/s. Then there is the mechanical watt, which is kilograms times square meters divided by seconds to the third power, so W = kg * m² / s³. Since a watt is a rather small amount, you often come across the term kilowatt, which corresponds to a thousand times the amount. But milli-, mega- and some other prefixes also appear frequently, since the power of very small to very large things is often an important value.

James Watt lived from 1736 to 1819 and worked on the steam engine, which was already known, but he improved it significantly and achieved a higher level of efficiency by using a separate condenser. He was already prominent during his lifetime, but he did not live to see his fame through the unit watt.