Resonant Frequency Calculator
Calculate the resonant frequency, inductance, or capacitance of a coil from any two values with the Resonant Frequency Calculator, and learn how with the integrated live example
The resonant frequency calculator can calculate the resonant frequency of a coil from the inductance and capacitance, calculate the inductance from the frequency and capacitance, or calculate the capacitance from the frequency and inductance.
Looking for the Coil Resonant Frequency Calculator?
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 and capacitance is constant. The relation between the two for a fixed frequency is called the L/C ratio. The resonant frequency formula is:
These units may be inconvenient when dealing with radio frequencies. An alternative formula is:
Example 1: Using the resonant frequency formula, find the resonant frequency of a circuit with an inductance of 3.2 µH and capacitance of 970pF
Example 2: Using the LC Constant formula, find the capacitance required to resonate at 1860 kc (1.86 Mc) with an inductance of 250 µH
The Resonant Frequency Calculator also uses the LC Constant to calculate the inductance or capacitance when the frequency is known. The LC Constant formula is:
Using the Resonant Frequency Calculator
Select whether to calculate the Frequency, Inductance, or Capacitance
Inductance: Input the inductance and select your preferred units
Capacitance: Input the capacitance and select your preferred units
Frequency: Input the frequency and select your preferred units
How To Calculate Resonant Frequency: This feature displays a live example of how to perform the calculation using the figures that you enter
The result is calculated and updated automatically as you enter different numbers or change between the input fields. If the calculated result hasn’t updated after you’ve finished entering your values, click or tap on the result.
Reference: ARRL – The Radio Amateur’s Handbook