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High Pass Filter Cutoff Calculator

Work out high pass filter cutoff instantly with clear inputs, formula shown and shareable results.

About High Pass Filter Cutoff Calculator

An RC high-pass filter uses the same cutoff formula, 1/(2 pi RC), but passes frequencies above it and blocks DC. Below cutoff the response falls at 6 dB per octave and phase leads, approaching 90 degrees far below cutoff.

Formula

RC high pass

fc = 1 / (2 pi R C); gain = 1 / sqrt(1 + (fc/f)^2)

Worked example

With the default values below, High Pass Filter Cutoff Calculator returns Cutoff frequency of 338.63. Change any input above and every figure here is recalculated in your browser.

Inputs used

Resistance
4,700 Ω
Capacitance
100 nF
Frequency of interest
100 Hz

Results

Cutoff frequency
338.63 Hz
Attenuation at that frequency
-10.96 dB
Phase shift
73.55 °
Time constant
0.47 ms

Step by step

  1. 1Values used
  2. 2RC high pass
  3. 3Cutoff frequency= 338.63 Hz
  4. 4Attenuation at that frequency= -10.96 dB
  5. 5Phase shift= 73.55 °
  6. 6Time constant= 0.47 ms

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

Why is a high-pass filter used for coupling?

It blocks DC bias while passing the signal, letting successive amplifier stages have independent operating points.

How low should the cutoff be for audio?

Well below the lowest wanted frequency — typically 10-20 Hz for full-range audio — because phase shift extends more than a decade above cutoff.

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