This tool calculates the cut-off frequency of a capacitor, within the context of a circuit, such as in an RC (resistor-capacitor) filter.

**Calculator**

**Formula**

**fc = 1/(2π*R*C)**

- fc is the cutoff frequency in Hertz (Hz)
- R is the resistance in Ohms (Ω)
- C is the capacitance in Farads (F)
- π is the mathematical constant Pi (approximately 3.14159)

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**Example Calculation**

The cutoff frequency for a RC network with R = 10 kΩ and C = 1 nF is 15.92 kHz. For a low pass filter, signals at frequencies above this value will be attenuated. For a high pass filter, signal frequencies below this value will be attenuated.

A schematic drawing of a simple low pass filter is shown below

And here is the frequency response

The calculator to find the 3 dB point shown above for R and C values.

**Background **

One of the most fundamental characteristics to calculate is the cutoff frequency (fc) of an RC filter. This is the frequency value at which the output signal drops to 70.7% (or -3 dB) of its input signal level for a low-pass or high-pass filter.