Power Calculator

Mechanical power is the rate of doing work, P = W / t, where W is work in joules and t is time in seconds. Dividing one joule by one second gives one watt. This mode is what you want for lifting, pushing, engines and any energy-over-time question.

Electrical power is P = V x I, where V is voltage in volts and I is current in amperes. One volt driving one ampere delivers one watt. Switch the calculator to Electrical mode to use this relationship instead of work over time.

Exactly two, within one mode. From any two of work, time and power, or any two of voltage, current and power, the third is fully determined. The 'Known values' menu lets you tell the tool which pair you are entering.

Yes. Choose a pair that includes power, such as Power + Time or Power + Voltage, and the calculator rearranges the formula for you. For example, Power + Voltage gives current as I = P / V, and Work + Power gives time as t = W / P.

SI base units: joules for work, seconds for time, volts for voltage, amperes for current and watts for power. Convert other units first, for instance turn minutes into seconds or kilojoules into joules, so the result comes out in plain watts.

One kilowatt is 1000 watts, and one mechanical horsepower is about 746 watts. So a 100 W result is 0.1 kW or roughly 0.134 hp. The calculator itself always reports watts, joules and seconds, so do any horsepower conversion afterwards.

Some rearrangements divide by the value you enter. Solving for power divides work by time, solving for current divides power by voltage, and solving for voltage divides power by current. A zero divisor is undefined, so the calculator rejects it with a short message.

P = V x I gives the true power for direct current and for purely resistive loads. In alternating-current circuits with inductors or capacitors you also need the power factor, so real power is V x I x cos(phi). This tool computes the straightforward V x I product.

All calculation happens in your browser, so nothing is sent to a server. Results are rounded to nine decimal places, which clears floating-point noise while keeping small values accurate.