RF Pi Attenuator Calculator

Use this tool to calculate Resistor values for a Pi attenuator.

Enter the desired value of attenuation and the characteristic impedance (default value is 50 ohm).


R1 = Zo [10dB/20 + 1] / [10dB/20 – 1]

R2 = Zo/2 [10dB/10 – 1] / [10dB/20]

where R1 is the shunt resistor and R2 is the series resistor. To build this attenuator you will need

  • two shunt resistors – one at the input and the other at the output
  • one series resistor