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About This Tool
Size passive first-order resistor-capacitor (RC) filters for audio crossover networks, sensor anti-aliasing, and power supply ripple decoupling. This calculator determines the -3dB cutoff corner frequency (fc) from component resistance (in kΩ) and capacitance (in nF) using standard analog circuit transfer equations fc = 1 / (2πRC).
How to Use
- 1
Select whether your circuit topology is a low-pass filter (series resistor, shunt capacitor) or high-pass filter (series capacitor, shunt resistor).
- 2
Enter the resistor value in kilo-ohms (kΩ) and the capacitor rating in nanofarads (nF).
- 3
Review the calculated -3dB corner cutoff frequency in hertz alongside RC time constant duration.
Frequently Asked Questions
What is the formula for calculating RC filter cutoff frequency?
The -3dB corner frequency is fc = 1 / (2πRC), where R is resistance in ohms and C is capacitance in farads. At fc, output signal amplitude drops by -3 dB (approximately 70.7% of input voltage).
What is a worked numerical example using standard audio filter values?
With a 10 kΩ resistor (10,000 Ω) and a 100 nF capacitor (0.0000001 F): 2πRC = 2 × π × 10,000 × 10⁻⁷ ≈ 0.006283 seconds. The cutoff frequency fc = 1 / 0.006283 ≈ 159.15 Hz.
What is the difference in signal response between low-pass and high-pass RC circuits?
A low-pass filter passes frequencies below fc while rolling off higher noise at -20 dB per decade. A high-pass filter blocks DC offsets and frequencies below fc while passing high-frequency signals.
Are analog circuit design parameters uploaded to an external server?
No. All corner frequency calculations and electrical conversions execute locally inside your web browser.