Passive RC Low-Pass / High-Pass Filter Cutoff Frequency (−3 dB) Calculator

Design passive first-order RC filters with exact −3 dB cutoff and phase shift.

−3 dB Cutoff Corner Frequency (f_c)
1,061.03 Hz
Attenuation at Test Frequency -6.58 dB
Phase Shift at Test Frequency -62.05 deg
Time Constant (τ = RC) 150 μs
Inputs
Ω
Filter resistor value (R) in Ohms (Ω).
nF
Filter capacitor value (C) in nanofarads (nF).
Hz
Operating signal frequency (f) in Hertz (Hz).
Results & Graph
−3 dB Cutoff Corner Frequency (f_c)
1,061.03 Hz
Attenuation at Test Frequency
-6.58 dB
Phase Shift at Test Frequency
-62.05 deg
Time Constant (τ = RC)
150 μs

−3 dB Cutoff Corner Frequency (f_c)

Graph 1 • Resistance Ohms Sensitivity Recalculates the domain equation across 50% to 150% of the primary input while holding other parameters constant.
0 Hz 1.1k Hz 2.3k Hz 50%: 2,122.07 Hz 2.1k 50% 75%: 1,414.71 Hz 1.4k 75% 100%: 1,061.03 Hz 1.1k 100% 125%: 848.83 Hz 848.8 125% 150%: 707.36 Hz 707.4 150%
Graph 2 • Primary & Supporting Metric Comparison Compares the primary output alongside supporting domain benchmarks.
−3 dB Cutoff Corner Frequency (f_c) 1,061.03 Hz Attenuation at Test Frequency -6.58 dB Phase Shift at Test Frequency -62.05 deg Time Constant (τ = RC) 150 μs
Graph 3 • Exact Output Table & Units Displays each calculated output in its exact domain unit.
−3 dB Cutoff Corner Frequency (f_c)1,061.03 HzAttenuation at Test Frequency-6.58 dBPhase Shift at Test Frequency-62.05 degTime Constant (τ = RC)150 μs
Summary: An RC network of 10000 Ω and 15 nF has τ = 150 μs and f_c = 1061.03 Hz (-6.58 dB at 2000 Hz).
Summary: An RC network of 10000 Ω and 15 nF has τ = 150 μs and f_c = 1061.03 Hz (-6.58 dB at 2000 Hz).
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Formula & Mathematical Methodology: RC Filter Cutoff Physics & Engineering Equation

fc = 1 / (2π × R × C)
|H(f)|dB = −10 × log₁₀[ 1 + (f / fc)² ]
f_c = 1 / (2π × R × C); |H(f)|_dB = −10 × log₁₀[ 1 + (f / f_c)² ]
  • resistanceOhms: Resistance Ohms (Ω)
  • capacitanceNanoFarad: Capacitance Nano Farad (nF)
  • testSignalFreqHz: Test Signal Freq Hz (Hz)

Rounding: Physical constants follow CODATA/NIST values; output quantities display to 2 decimal places.

Worked Example: Physics & Engineering Benchmark: RC Filter Cutoff

Design passive first-order RC filters with exact −3 dB cutoff and phase shift.

  1. Enter the physical dimensions, electrical parameters, or thermodynamic state variables.
  2. Apply the governing equation: f_c = 1 / (2π × R × C); |H(f)|_dB = −10 × log₁₀[ 1 + (f / f_c)² ].
  3. Inspect the primary SI output, derived quantities, and 3 visual SVG graphs.
Result: Computes RC Filter Cutoff via f_c = 1 / (2π × R × C); |H(f)|_dB = −10 × log₁₀[ 1 + (f / f_c)² ].

Frequently Asked Questions

What equation powers the Passive RC Low-Pass / High-Pass Filter Cutoff Frequency (−3 dB) Calculator?

It evaluates f_c = 1 / (2π × R × C); |H(f)|_dB = −10 × log₁₀[ 1 + (f / f_c)² ] using IEEE-754 double precision and renders three synchronized SVG plots.

Can I test parameter sensitivity across multiple values?

Yes. Graph 1 automatically plots a 50%–150% parameter response curve, and you can pin up to 3 custom scenarios.

Are all units consistent with SI standards?

Yes. Each input field specifies its exact SI or engineering unit and converts internally where needed.

Science & Engineering · Electrical & RF Engineering

Passive RC Low-Pass / High-Pass Filter Cutoff Frequency (−3 dB) Calculator: inputs, method, and how to read the result

Design passive first-order RC filters with exact −3 dB cutoff and phase shift.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Resistance Ohms: Filter resistor value (R) in Ohms (Ω).
  • Capacitance Nano Farad: Filter capacitor value (C) in nanofarads (nF).
  • Test Signal Freq Hz: Operating signal frequency (f) in Hertz (Hz).

What the calculation includes

With the default values shown, −3 dB Cutoff Corner Frequency (f_c) is 1,061.03 Hz. The calculation follows RC Filter Cutoff Physics & Engineering Equation; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Resistance Ohms from 10,000 Ω to 11,000 Ω changes −3 dB Cutoff Corner Frequency (f_c) from 1,061.03 Hz to 964.58 Hz. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard SI physical constants (g = 9.80665 m/s², c = 299,792,458 m/s, σ = 5.670374×10⁻⁸ W·m⁻²·K⁻⁴).
  • Engineering reference model; apply appropriate safety factors and empirical calibration for critical hardware designs.

Scope: SI / NIST Physics & Engineering Standard Check the assumptions and limitations against your situation before relying on the estimate.

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