Cutoff Frequency Calculator

Find cutoff frequency using resistors, capacitors, inductors, or waveguide modes quickly here. See angular values, time constants, and exports for reports and sharing easily.

Calculator Inputs

Choose the model that matches your setup.
Your preferred unit for the displayed cutoff.
Used for RC and RL calculations.
For RC: cutoff depends on R and C.
For RL: cutoff depends on R and L.
Waveguide inside dimension a.
Waveguide inside dimension b.
Example TE10 uses m=1, n=0.
Set to 1 for air‑filled guides.
Usually close to 1 for common dielectrics.
Reset

Formula Used

  • RC (first‑order): fc = 1 / (2πRC), with time constant τ = RC.
  • RL (first‑order): fc = R / (2πL), with time constant τ = L / R.
  • Rectangular waveguide: fc = (c/2) √[(m/a)² + (n/b)²], where c = c₀ / √(εr μr).

Angular cutoff is ωc = 2πfc for all cases.

How to Use This Calculator

  1. Select the calculator type that matches your circuit or guide.
  2. Enter component values or dimensions, then choose units.
  3. Pick a display unit for the cutoff frequency.
  4. Press Calculate to show results above the form.
  5. Use the CSV or PDF buttons to export the last result.

Example Data Table

Case Inputs Computed fc
RC R = 1 kΩ, C = 0.1 µF 1,591.55 Hz
RC R = 4.7 kΩ, C = 10 nF 3,386.28 Hz
RC R = 10 kΩ, C = 1 nF 15,915.49 Hz
RL R = 10 Ω, L = 10 mH 159.15 Hz
Waveguide a = 22.86 mm, b = 10.16 mm, mode (1,0), εr=1, μr=1 6.557 GHz

Examples are rounded for readability; your output may differ slightly.

Notes for Better Accuracy

  • For RC and RL, use measured component values when possible.
  • For waveguides, use internal dimensions and correct dielectric properties.
  • Cutoff is a boundary; behavior changes gradually around it.

Accurate cutoff values help you design cleaner, safer systems.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.