# Capacitive Reactance Calculator

Our capacitive reactance calculator allows you to **obtain the opposition to current flow introduced by a capacitor in an AC circuit**.

If you don't know what *capacitive reactance* and *impedance* are, you've come to the right place. In this short text, we will cover:

**Capacitive reactance definition**(sometimes called capacitor resistance);**Capacitive reactance formula**; and- How to easily
**calculate capacitive reactance**.

## What is capacitive reactance?

As a capacitor **charges up** in a **DC** circuit, the charges accumulating on the capacitor plates will begin to **oppose the current flow until it reaches zero** (*see* *force between two charges*).

In **AC** circuits, however, capacitors are constantly being charged and discharged, so this opposition to current is present at all times. We call this resistance to current flow the **capacitive reactance**, and we measure it in **ohms Ω**.

🙋 Keep in mind that, while they are similar, **resistance only applies to resistors**, while **capacitive reactance is a property of capacitors**. That's why "capacitor resistance" does not accurately describe this phenomenon.

Let's now see how to calculate the capacitive reactance.

## How to calculate capacitive reactance

We can quickly obtain the capacitive reactance of a capacitor with the **capacitive reactance formula**:

where:

- $f$ is the
**frequency**of the power supply; - $C$ is the capacitor's
**capacitance**; and - $X$ is the
**capacitive reactance**, in ohms.

Alternatively, we can use the **angular frequency** $\omega$:

As you can see, **increasing the frequency will decrease the capacitive reactance**.

At the same time, **increasing the capacitance of the capacitor will also lower its capacitive reactance**.

**Why?** Remember what we discussed at the beginning: as a capacitor is being **charged**, it allows current to *flow* freely through it and *gradually slows down* when near fully charged.

If the capacitor is large enough or if we don't give it enough time to charge, **the charges won't be able to pile up** on the capacitor plates, and **stop** the current flow, thus **increasing** the current in the circuit!