# LC Constant Calculator

### Use the LC Constant Calculator below to calculate either the inductance or capacitance required in order to resonate a circuit at any frequency

The formula for the resonant frequency of a circuit shows that the same frequency will always be obtained as long as the product of the inductance (L) and capacitance (C) is constant. The relation between the two for a fixed frequency is called the L/C ratio.

When the frequency is known, **and** either the inductance **or** the capacitance is known, you can calculate the unknown quantity using the LC Constant Calculator. The inductance or capacitance required for resonance at any frequency is given by the equation:

Where

L = Inductance in microhenrys (µH)

C = Capacitance in picofarads (pF)

F = Frequency in megacycles (Mc) or megahertz (MHz)

**Example 1:** Find the capacitance required to resonate at 1860 kc (1.86 Mc) with an inductance of 250 µH

**Example 2:** Find the inductance required to resonate at 570 kc (0.57 Mc) with a capacitance of 1500 pF

### Using the LC Constant Calculator

**Frequency:** You must enter a frequency for the calculator to work

**Calculating inductance:** To calculate the inductance, **input the capacitance** into the green capacitance cell

**Calculating capacitance:** To calculate the capacitance, **input the inductance** into the green inductance cell

**Units:** You can choose your preferred units of measurement through selecting the units cells and clicking the arrow to display a list of available options

*Reference: ARRL – The Radio Amateur’s Handbook*

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