RC Low-Pass Filter Calculator

This is a small-signal educational model; source/load impedance and non-ideal component behavior can change a real circuit.

Resistance

Capacitance

Probe frequency

—Low-pass cutoff frequency (−3 dB point)

—Gain at probe

—Voltage ratio

—Phase

—Time constant

Ideal first-order RC model

The calculator uses the ideal cutoff relation f_c = 1/(2πRC) plus the standard first-order transfer magnitude and phase.

Real loading changes the response

Source resistance, load impedance, capacitor ESR/tolerance and parasitics can move the measured response. Treat this as educational small-signal analysis, not safety guidance.