Power Calculator

What is Power?

Power is the rate at which energy is transferred, converted, or work is performed. It is a fundamental physical quantity that describes how quickly a system can do work or deliver energy. In the International System of Units (SI), power is measured in watts (W), where one watt equals one joule per second.

Our Power Calculator is a versatile tool that computes power using multiple physical relationships. Whether you know voltage and current (electrical power), force and velocity (mechanical power), torque and angular velocity (rotational power), or work and time, the calculator handles the conversions and returns results in watts, kilowatts, horsepower, BTU/hour, and other common units.

How to Use the Power Calculator

Select the calculation mode that matches your known parameters:

• Electrical Mode: Enter voltage (volts) and current (amps). Optionally include power factor for AC circuits.
• Mechanical Mode: Enter force (newtons) and velocity (meters per second).
• Rotational Mode: Enter torque (newton-meters) and angular speed (RPM).
• Work/Time Mode: Enter work done (joules) and the time interval (seconds).

Key Power Formulas

The calculator supports these fundamental relationships:

Electrical Power (DC): $$P = V \times I$$

Electrical Power (AC single-phase): $$P = V \times I \times \cos\phi$$

Mechanical Power from Force and Velocity: $$P = F \times v$$

Rotational Power from Torque and RPM: $$P = \tau \times \frac{2\pi \times RPM}{60}$$

Power from Work and Time: $$P = \frac{W}{t}$$

Common Unit Conversions

Power is expressed in many different units depending on the field:

• 1 watt (W) = 1 joule per second
• 1 kilowatt (kW) = 1,000 watts
• 1 mechanical horsepower (hp) = 745.7 watts
• 1 metric horsepower (PS) = 735.5 watts
• 1 BTU/hour = 0.2931 watts

Also check: Work Calculator, Force Calculator, Speed Calculator, Energy Cost Calculator, Resistor Calculator, Pump Calculator.