Calculate the cutoff frequency of a passive RC low-pass or high-pass filter.
Filter Components
Cutoff Frequency
Enter R and C values
About this calculator
Quick Reference
fcCutoff Frequency (Hz)
RResistance (Ω)
CCapacitance (F)
τTime Constant (RC)
Overview
Passive RC filters are simple circuits used to allow certain frequencies to pass while attenuating others. The cutoff frequency is the point where the signal power is reduced by half (-3 dB).
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Pro Tips
Cutoff Frequency formula: fc = 1 / (2πRC)
Low Pass Filter: Allows frequencies below fc to pass.
High Pass Filter: Allows frequencies above fc to pass.
At the cutoff frequency, the output voltage is ~70.7% of the input voltage.
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Fun Facts
"RC filters are 'first-order' filters, meaning the attenuation increases by 6 dB per octave (or 20 dB per decade) beyond the cutoff."
"They are commonly used in audio equipment to separate bass (low pass) and treble (high pass) frequencies."
