How to use the rc filter cutoff frequency calculator
Find the cutoff frequency of an RC low-pass or high-pass filter. Enter resistance, capacitance in the fields above; the cutoff frequency, time constant are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “low pass filter”, “audio filter”, “3db point”, “calculate rc filter cutoff frequency”, “find cutoff frequency”.
Formula
Variables
- R — Resistance (kΩ)
- C — Capacitance (nF)
Worked example
With resistance = 10 kΩ, capacitance = 10 nF, the calculator gives cutoff frequency ≈ 1,591.549 Hz; time constant ≈ 100 µs.
Frequently asked questions
What is the rc filter cutoff frequency calculator used for?
Find the cutoff frequency of an RC low-pass or high-pass filter. It helps with questions such as “low pass filter”, “audio filter”, “3db point”.
What is the formula for the rc filter cutoff frequency calculation?
Cutoff frequency (Hz) = 1 / (2 × π × R × 1000 × C × 1e-9). Time constant (µs) = R × C. Here R is resistance (kΩ), C is capacitance (nF).
What inputs do I need for the rc filter cutoff frequency calculator?
You need resistance in kΩ, capacitance in nF. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the rc filter cutoff frequency calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the rc filter cutoff frequency result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.