RC Low-Pass Filter Calculator Enter any two values (Frequency, Resistance, Capacitance) and leave one blank. Choose appropriate units to calculate the missing value. Cutoff Frequency: HzkHzMHz Resistance (R): ΩkΩMΩ Capacitance (C): FμFnFpF Calculate Clear Note: The cutoff frequency is calculated using f = 1 / (2πRC). Use standard values for best results in real circuits.