Attenuator Pad Calculator

Calculate resistor values for T-pad, Pi-pad, and Bridged-T attenuator networks with power dissipation analysis.

What is an Attenuator?

An attenuator is a volume knob for RF signals — it reduces signal strength by a precise, controlled amount using a network of resistors. Unlike simply disconnecting an antenna, a good attenuator maintains the correct impedance so the rest of the circuit behaves normally.

Why it matters: Test labs use attenuators to simulate weak signals and verify that receivers work correctly at long range. A 20 dB attenuator makes a signal 100× weaker — letting engineers test without actually moving equipment miles apart.

Pad Configuration
Select topology and enter design parameters.
dB

How much to reduce the signal. 10 dB = 10× weaker, 20 dB = 100× weaker

Ω

The impedance of the source driving the attenuator. Most RF systems use 50 Ω

Ω

The impedance of the load the attenuator drives. Usually 50 Ω for RF, 75 Ω for cable TV

dBm

Signal power going in — used to calculate how much heat each resistor must handle

Resistor Values — T-pad
10 dB · 50 Ω → 50 Ω
25.97 Ω25.97 Ω35.14 ΩINOUTR1R3R2

R1 (series, input)

Dissipates 0.52 mW (51.9%)

25.97 Ω

R2 (shunt)

Dissipates 0.33 mW (32.9%)

35.14 Ω

R3 (series, output)

Dissipates 0.05 mW (5.2%)

25.97 Ω

Input Power

1.00 mW

Output Power

0.100 mW

For asymmetric impedances, values are approximated using the geometric mean impedance method. Use standard resistor values (E24/E96 series) in practice and verify with simulation. Bridged-T maintains constant impedance across attenuation range.