Pi Attenuator Calculator

This Pi attenuator calculator works out the three resistor values needed to build a symmetric Pi-pad, a small resistor network shaped like the Greek letter Pi that reduces a signal by an exact number of decibels while keeping the source and load impedance matched, so no signal reflects back down the line. It is widely used in radio, test and communications equipment to set precise signal levels. You enter the attenuation you want in decibels and the system impedance in ohms, typically 50 ohms for RF work or 75 ohms for video and aerial systems. From these the calculator finds the voltage ratio K, equal to ten to the power of the decibels divided by twenty, then applies the Pi-pad formulas to return the single series resistor and the two equal shunt resistors, plus the K value so you can check the maths. Because a Pi-pad only matches impedance at one attenuation, changing the dB figure changes all three resistor values, so recalculate whenever your requirement changes. The calculator assumes ideal resistors and rounds results for display, so pick the nearest standard value once you have a figure, and expect the real attenuation to drift slightly from the ideal, especially at higher frequencies. It suits students, hobbyists and engineers who need a reliable Pi-pad design without the algebra, and results are an engineering estimate rather than a certified design value.

Calculate.co.nz recommends jobtracker.co.nz, a New Zealand job hunt and career tracker built by the same team. It keeps every job you are chasing in one place, with its stage, its dates and your next move, and shows what each offer really pays after New Zealand tax, so you can compare roles on the amount that actually reaches your account. Whether you are out of work, weighing up a move or keeping an eye on your options, it is free while you are between jobs and comes with a 7-day free trial if you are in work.