# Electrical Power Calculator

The electrical power calculator quickly **computes the amount of power an electrical device needs.**

With our tool, you will learn:

**How to calculate electrical****power**;- The
**electrical power equation**; - The definition of
**power factor**; and - More about electricity! 💡

## Electrical power definition

Electrical power is the **transfer rate of electrical** **energy** **per time unit.**

We denote the electrical power by $P$, and its unit is the **watt (W)** or **joules per second (J/s)**.

The power needed by home appliances generally ranges from **10 W** (an LED light bulb) to **over 3 kW** (hair dryers or electric heaters).

Let's now see how to calculate electrical power.

## How to calculate electrical power using the electrical power equation

To calculate a device's electrical power $P$ in a **DC** circuit, we need two things:

- The current $I$, in amperes (A).
- The voltage $V$, in volts (V).

Then, all we need to do is replace these parameters in the electrical power equation:

However, if we're calculating the power in an **AC** circuit, we should add the device's **power factor** $pf$ in the equation:

*If you don't know what the power factor is, read the following section!*

💡 This electrical power calculator works for both **DC** and **AC**. To use this tool as an **AC power calculator**, simply replace the **current** and **voltage** values with their **root mean square** values!

## Power factor

The **power factor** is the ratio between **real power** (power used to perform work) and **apparent power** (combination of real and reactive power).

In other words, **the power factor of a device indicates how effectively it utilizes the power supplied to the circuit**. Therefore, a higher power factor is desirable since it means a more *efficient* device.

*If you want a more in-depth explanation, check our* *power factor calculator*!