RC Low-Pass Filter
Calculate, visualize, and hear a low-pass filter
First-order RC low-pass filter with live calculator, Bode magnitude/phase plots, and real-time audio demo. Fully client-side, no tracking.
fc = 1 / (2πRC)
Calculator
Compute the cutoff frequency or solve for a missing component. Use SI units below for convenience.
Formula
fc = 1 / (2πRC)
At fc the output magnitude is -3 dB. The slope approaches -20 dB/dec from low to high frequencies.
- Impedance of capacitor: |Xc| = 1 / (2πfC)
- Transfer function: H(jω) = 1 / (1 + jωRC)
- Magnitude: |H| = 1 / √(1 + (ωRC)²)
- Phase: φ = −arctan(ωRC)
Bode plots
Audio demo
Hear how the low-pass filter affects a tone or noise. The cutoff is synced to your calculator values by default.
Hz
Wet/Dry mix
Tip
Try a high frequency tone (e.g., 5 kHz) and decrease the cutoff. You’ll hear highs attenuate while bass passes through.