# Resonant Frequency Calculator

Our resonant frequency calculator can easily **obtain the resonant frequency of an LC circuit**.

If you are trying to better understand this electromagnetism topic, **you've come to the right place**. We will explain everything you need to know about these circuits, including:

- Resonant frequency definition;
- How to calculate the resonant frequency of an LC circuit (series and parallel); and
- The resonant frequency formula.

Keep reading below!

## LC circuits ─ What is the resonant frequency?

An LC circuit is any type of circuit (**series** or **parallel**) consisting of an inductor and a capacitor.

The resonant frequency of an **LC** circuit is reached when **the inductive and capacitive reactances are equal in magnitude**. At this frequency, the current is either at its *maximum* or *minimum* value, depending on the type of circuit.

An **LC** circuit connected in *series* works with **minimum impedance** at the resonant frequency. On the other hand, when connected in *parallel*, it possesses **maximum impedance** at the resonant frequency.

Let's look at how to find the resonant frequency of an LC circuit.

💡 **RLC circuits** use this to create **band-pass** or **band-stop** filters! Read more about RLC circuits in our RLC circuit calculator.

## How to calculate the resonant frequency of an LC circuit

As we said before, in **LC** circuits, *the inductive and capacitive reactances* ($X_{L}$ and $X_{C}$ respectively) *are equal in magnitude at the resonant frequency*. We can use this bit of information to find the resonant frequency equation:

solving for $f$, we obtain the **resonant frequency formula**:

where:

- $f$ is the
**resonant frequency**; - $L$ is the
**inductance**; and - $C$ is the
**capacitance**.

You can also obtain the **angular frequency** using the `advanced-mode`

of this resonant frequency calculator or by hand using the following formula:

## How to use the resonant frequency calculator

To use our tool, you simply need to input the capacitance (C) of the capacitor and the inductance (L) of the inductor. That's it!

For example, if we had a $1\ \text{pF}$ capacitor in series with a $2\ \text{μH}$ inductor, we can see that the resulting resonant frequency is $112.54\ \text{MHz}$.

And, using the `advanced-mode`

, we can check the values for the capacitive and inductive reactances.