basic

RC Low-Pass Cutoff Frequency Calculator

f_c = 1 / (2π · R · C) for an RC low-pass filter.

Compute the −3 dB cutoff frequency of an RC low-pass (or high-pass) filter from the resistor and capacitor values, plus the time constant τ = R·C and the filter response at a chosen test frequency.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

Ω
µF
Hz

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

f_c = 1 / (2π · R · C); |H(f)| = 1 / √(1 + (f / f_c)²).

In depth

Compute the −3 dB cutoff frequency of an RC low-pass (or high-pass) filter from the resistor and capacitor values, plus the time constant τ = R·C and the filter response at a chosen test frequency.